Institut für Informatik und Computational Science
Refine
Year of publication
Document Type
- Article (534)
- Doctoral Thesis (125)
- Monograph/Edited Volume (82)
- Other (26)
- Postprint (10)
- Conference Proceeding (5)
- Part of a Book (4)
- Preprint (4)
- Bachelor Thesis (1)
- Habilitation Thesis (1)
Language
- English (793) (remove)
Is part of the Bibliography
- yes (793) (remove)
Keywords
- answer set programming (12)
- Answer Set Programming (10)
- Answer set programming (10)
- Machine Learning (7)
- Maschinelles Lernen (7)
- Antwortmengenprogrammierung (5)
- Internet of Things (4)
- MQTT (4)
- machine learning (4)
- security (4)
- Algorithms (3)
- EEG (3)
- Equilibrium logic (3)
- Machine learning (3)
- Modeling (3)
- Optimization (3)
- formal languages (3)
- higher education (3)
- monitoring (3)
- verification (3)
- 3D visualization (2)
- ASIC (2)
- Algorithmen (2)
- Analytical models (2)
- Automata systems (2)
- Computersicherheit (2)
- Deep Learning (2)
- E-learning (2)
- Event mapping (2)
- Fault tolerance (2)
- ICA (2)
- Informatik (2)
- Knowledge Representation and Reasoning (2)
- Künstliche Intelligenz (2)
- Lindenmayer systems (2)
- Middleware (2)
- Modell (2)
- Modellierung (2)
- Non-monotonic reasoning (2)
- Ontologie (2)
- Parameterized complexity (2)
- Preference Handling (2)
- Process (2)
- Process mining (2)
- Prozess (2)
- ResNet (2)
- Semantic Web (2)
- Theory (2)
- Tracking (2)
- Treewidth (2)
- Vorhersage (2)
- anti-cancer drugs (2)
- argument mining (2)
- automatic feedback (2)
- bioinformatics (2)
- computer science education (2)
- concurrent checking (2)
- cooperating systems (2)
- deep neural networks (2)
- drug-sensitivity prediction (2)
- edge computing (2)
- embedded systems (2)
- face tracking (2)
- facial expression (2)
- firmware update (2)
- geovisualization (2)
- image processing (2)
- lesson planning (2)
- lesson preparation (2)
- logic programming (2)
- maschinelles Lernen (2)
- model (2)
- non-photorealistic rendering (2)
- online learning (2)
- parsing (2)
- perception (2)
- perception differences (2)
- physical computing (2)
- policy evaluation (2)
- radhard design (2)
- reliability (2)
- scientific workflows (2)
- self-adaptive multiprocessing system (2)
- single event upset (2)
- solar particle event (2)
- support system (2)
- systems biology (2)
- teacher training (2)
- virtual mobility (2)
- 'Peer To Peer' (1)
- (FPGA) (1)
- (SET) count rate (1)
- 13C metabolic flux analysis (1)
- 2-tag system (1)
- 3D Computer Grafik (1)
- 3D Computer Graphics (1)
- 3D Drucken (1)
- 3D Linsen (1)
- 3D Semiotik (1)
- 3D Visualisierung (1)
- 3D lenses (1)
- 3D modeling (1)
- 3D printing (1)
- 3D semiotics (1)
- 3D-Stadtmodelle (1)
- 3d city models (1)
- 6LoWPAN (1)
- AODV (1)
- ASIC (Applikationsspezifische Integrierte Schaltkreise) (1)
- ASP (Answer Set Programming) (1)
- Abbrecherquote (1)
- Absorbed dose (1)
- Abstraction (1)
- Abstraktion (1)
- Accepting Grammars (1)
- Access control (1)
- Ackerschmalwand (1)
- Active Evaluation (1)
- Active evaluation (1)
- Ad hoc routing (1)
- Adaptivity (1)
- Advanced Video Codec (AVC) (1)
- Adversarial Learning (1)
- Aggregates (1)
- Aktive Evaluierung (1)
- Akzeptierende Grammatiken (1)
- Algorithm configuration (1)
- Algorithm portfolios (1)
- Algorithmenablaufplanung (1)
- Algorithmenkonfiguration (1)
- Algorithmenselektion (1)
- Alignment (1)
- Android Security (1)
- Android hybrid apps (1)
- Angewandte Spieltheorie (1)
- Animal building (1)
- Anisotroper Kuwahara Filter (1)
- Anleitung (1)
- Answer Set Solving modulo Theories (1)
- Anti-cancer drugs (1)
- Antwortmengen Programmierung (1)
- Applied Game Theory (1)
- Argumentation (1)
- Argumentation structure (1)
- Artificial Intelligence (1)
- Artificial Neuronal Network (1)
- Assessment (1)
- Asynchrone Schaltung (1)
- Augenbewegungen (1)
- Augmentation (1)
- Augmented and virtual reality (1)
- Ausreissererkennung (1)
- Automated parallelization (1)
- Automatically controlled windows (1)
- BCI (1)
- BSS (1)
- Bachelorstudierende der Informatik (1)
- Backdoors (1)
- Batch processing (1)
- Baumweite (1)
- Bean (1)
- Behavior (1)
- Benchmark testing; (1)
- Berührungseingaben (1)
- Beweis (1)
- Beweisassistent (1)
- Beweistheorie (1)
- Beweisumgebung (1)
- Bilddatenanalyse (1)
- Bildung (1)
- Bildverarbeitung (1)
- Binäres Entscheidungsdiagramm (1)
- Bio-jETI (1)
- Bioelektrisches Signal (1)
- Bioinformatik (1)
- Blind users (1)
- Boolean constraint solver (1)
- Boolean logic models (1)
- Boosting (1)
- Bot Detection (1)
- Brain Computer Interface (1)
- Business Process (1)
- Business Process Models (1)
- Business process intelligence (1)
- CASP (Constraint Answer Set Programming) (1)
- CP-Logic (1)
- CSC (1)
- Cactus (1)
- Campus (1)
- Choreographien (1)
- Circuit faults (1)
- Classification (1)
- Clock tree (1)
- Cloud (1)
- Cluster Computing (1)
- Cluster computing (1)
- Clusteranalyse (1)
- Code generation (1)
- Coherent phonons (1)
- Combinatorial multi-objective optimization (1)
- Common Spatial Pattern (1)
- Complex optimization (1)
- Complexity (1)
- Compliance (1)
- Composition (1)
- Computational Complexity (1)
- Computational complexity (1)
- Computational grid (1)
- Computer Science (1)
- Computer Science Education (1)
- Computer security (1)
- Computergrafik (1)
- Computing with DNA (1)
- Conformant Planning (1)
- Conrad Hal Waddington (1)
- Constraint Solving (1)
- Constraint satisfaction (1)
- Context awareness (1)
- Contextualized learning (1)
- Continuous Testing (1)
- Continuous Versioning (1)
- Controlled Derivations (1)
- Convolution (1)
- Coq (1)
- Course timetabling (1)
- Covariate Shift (1)
- Curry (1)
- Customer ownership (1)
- D-galactosamine (1)
- DDoS (1)
- DMR (1)
- DNA hairpin formation (1)
- DPLL (1)
- DRMAA (1)
- DRMS (1)
- Data federation (1)
- Database (1)
- Deal of the Day (1)
- Debugging (1)
- Decidability (1)
- Declarative Problem Solving (1)
- Declare (1)
- Deduction (1)
- Deep learning (1)
- Defining characteristics of physical computing (1)
- Dempster-Shafer-Theorie (1)
- Dempster–Shafer theory (1)
- Denotational semantics (1)
- Description Logics (1)
- Design (1)
- Design for testability (DFT) (1)
- Deskriptive Logik (1)
- Diagonalisierung (1)
- Didaktik der Informatik (1)
- Dienstkomposition (1)
- Dienstplattform (1)
- Differenz von Gauss Filtern (1)
- Digital Design (1)
- Digital image analysis (1)
- Digitalization (1)
- Distributed Computing (1)
- Dose rate (1)
- Double cell upsets (DCUs) (1)
- Dynamic Programming (1)
- Dynamical X-ray theory (1)
- Dynamische Programmierung (1)
- Dynamische Rekonfiguration (1)
- E-Learning (1)
- E-teaching (1)
- EDC (1)
- Echtzeitanwendung (1)
- Edge Computing (1)
- Educational game (1)
- Educational timetabling (1)
- Eingabegenauigkeit (1)
- Elektroencephalographie (1)
- Emotionen (1)
- Emotionsforschung (1)
- Encoding (1)
- Engines (1)
- Enterprise Architecture (1)
- Entity Linking (1)
- Entscheidungsbäume (1)
- Entwurfsmuster für SOA-Sicherheit (1)
- Entwurfsprinzipien (1)
- Epigenetic landscape (1)
- Epistemic Logic Programs (1)
- Erfüllbarkeit einer Formel der Aussagenlogik (1)
- Erfüllbarkeitsproblem (1)
- Erklärbarkeit (1)
- Error Estimation (1)
- European Bioinformatics Institute (1)
- Evaluation (1)
- Evidenztheorie (1)
- Evolution (1)
- Experimentation (1)
- Explainability (1)
- Explicit negation (1)
- Exploration (1)
- Explore-first Programming (1)
- Exponential Time Hypothesis (1)
- Exponentialzeit Hypothese (1)
- Extensibility (1)
- Extreme Model-Driven Development (1)
- FEDC (1)
- FMC-QE (1)
- FPGA (1)
- Fault Localization (1)
- Fault tolerant systems (1)
- Feature Combination (1)
- Feature extraction (1)
- Feedback (1)
- Fehlende Daten (1)
- Fehlerschätzung (1)
- Field programmable gate arrays (1)
- Finite automata (1)
- Flip-flops (1)
- Flussgesteuerter Bilateraler Filter (1)
- Focus+Context Visualization (1)
- Fokus-&-Kontext Visualisierung (1)
- Forgetting (1)
- Formalismus (1)
- Formalitätsgrad (1)
- Formeln der quantifizierten Aussagenlogik (1)
- Framework (1)
- Freshmen (1)
- GERBIL (1)
- GIS-Dienstkomposition (1)
- GPU (1)
- Gebäudemodelle (1)
- Gehirn-Computer-Schnittstelle (1)
- Geländemodelle (1)
- Generalisierung (1)
- Geodaten (1)
- Geometrieerzeugung (1)
- Geovisualisierung (1)
- Geschäftsprozess (1)
- Geschäftsprozessmodelle (1)
- Gesichtsausdruck (1)
- Gesteuerte Ableitungen (1)
- Gesture input (1)
- Gleichheit (1)
- Globus (1)
- Grammar Systems (1)
- Grammatiksysteme (1)
- Graph Convolutional Neural Networks (1)
- Graph Embedding (1)
- Green computing (1)
- Grid (1)
- Grid Computing (1)
- Grounded theory (1)
- Grounding Theory (1)
- H.264 (1)
- HCI (1)
- Hairpin completions (1)
- Hairpin reductions (1)
- Hardware Design (1)
- Hardware accelerator (1)
- Hauptkomponentenanalyse (1)
- Heat diffusion (1)
- Hierarchically configurable mask register (1)
- High-Level Synthesis (1)
- Histograms (1)
- Hochschulsystem (1)
- Https traffic (1)
- Human Factors (1)
- Hurricane Sandy (1)
- Hybrid App (1)
- I/O-effiziente Algorithmen (1)
- ICT (1)
- IP core (1)
- IT security (1)
- IT-Security (1)
- IT-Sicherheit (1)
- IaaS (1)
- Identifiers (1)
- Image and video stylization (1)
- Image resolution (1)
- Imperative calculi (1)
- Improving classroom (1)
- Incoherent phonons (1)
- Incremental answer set programming (1)
- Industrie 4.0 (1)
- Industry 4.0 (1)
- Inference (1)
- Informatics (1)
- Informatik-Studiengänge (1)
- Informatikdidaktik (1)
- Informatikvoraussetzungen (1)
- Information Transfer Rate (1)
- Information federation (1)
- Information integration (1)
- Information retrieval (1)
- Information security (1)
- Inkonsistenz (1)
- Insurance industry (1)
- Integrated circuit modeling (1)
- Integration (1)
- Interactive Rendering (1)
- Interaktionsmodel (1)
- Interaktionsmodellierung (1)
- Interaktives Rendering (1)
- Interface design (1)
- Internet (1)
- Internet Security (1)
- Internet-Sicherheit (1)
- Interoperability (1)
- Interoperabilität (1)
- Interpretability (1)
- Interpretierbarkeit (1)
- IoT (1)
- Job monitoring (1)
- Job submission (1)
- Kartografisches Design (1)
- Kern-PCA (1)
- Kernel (1)
- Kernelization (1)
- Kernmethoden (1)
- Key Competencies (1)
- Key input (1)
- Klassifikation (1)
- Klassifikation mit großem Margin (1)
- Klassifikator-Kalibrierung (1)
- Klimafolgenanalyse (1)
- Klimawandel (1)
- Knowledge (1)
- Knowledge Management (1)
- Knowledge representation (1)
- Kommunikation (1)
- Komplexität (1)
- Komplexitätsbewältigung (1)
- Komplexitätstheorie (1)
- Komposition (1)
- Konnektionskalkül (1)
- Kybernetik (1)
- Künstliche Neuronale Netzwerke (1)
- L systems (1)
- LBA problem (1)
- Landmark visibility (1)
- Landmarken (1)
- Large Margin Classification (1)
- Laser Cutten (1)
- Learning (1)
- Leftmost Derivations (1)
- Lehrer (1)
- Leistungsvorhersage (1)
- Lernen (1)
- Linksableitungen (1)
- Literature mining (1)
- Liver neoplasms (1)
- Load Balancing (1)
- Localization (1)
- Location awareness (1)
- Logic Programming (1)
- Logic programming (1)
- Logics (1)
- Logik (1)
- Logiksynthese (1)
- Loss (1)
- Low Latency (1)
- Lower Bounds (1)
- Loyalty (1)
- M2M (1)
- MEG (1)
- MFA (1)
- Magnetoencephalographie (1)
- Malware (1)
- Markov processes (1)
- Masking of X-values (1)
- Mathematical Optimization (1)
- Mathematikdidaktik (1)
- Mathematikphilosophie (1)
- Mathematische Optimierung (1)
- Matrizen-Eigenwertaufgabe (1)
- Media in education (1)
- Megamodel (1)
- Megamodell (1)
- Mehrklassen-Klassifikation (1)
- Message Passing Interface (1)
- Meta-Programming (1)
- Metric learning (1)
- Migration (1)
- Minimal perturbation problems (1)
- Mischmodelle (1)
- Mischung <Signalverarbeitung> (1)
- Mobile Campus Application (1)
- Mobile application (1)
- Mobile devices (1)
- Mobile learning (1)
- Mobilgeräte (1)
- Model Management (1)
- Model checking (1)
- Model-Driven Engineering (1)
- Modell Management (1)
- Modell-driven Security (1)
- Modell-getriebene Sicherheit (1)
- Modellgetriebene Entwicklung (1)
- Modelling (1)
- Molekulare Bioinformatik (1)
- Multi Task Learning (1)
- Multi-Class (1)
- Multi-Task-Lernen (1)
- Multi-objective optimization (1)
- Multi-sided platforms (1)
- Multiple interpretation scheme (1)
- Multiprocessor (1)
- Multiprozessor (1)
- N-temperature model (1)
- NETCONF (1)
- NUI (1)
- Nash equilibrium (1)
- Natural language processing (1)
- Natural ventilation (1)
- Network (1)
- Network Management (1)
- Network security (1)
- Netzwerk Management (1)
- Netzwerke (1)
- Neural networks (1)
- Neuronales Netz (1)
- Next Generation Network (1)
- Nicht-photorealistisches Rendering (1)
- Nichtfotorealistische Bildsynthese (1)
- Non-Monotonic (1)
- Nonmonotonic reasoning (1)
- Nutzungsinteresse (1)
- OCCI (1)
- OSSE (1)
- Objektive Schwierigkeit (1)
- Omega (1)
- Ontologien (1)
- Ontologies (1)
- Ontology (1)
- Operation problem (1)
- Optimierung (1)
- Optimierungsproblem (1)
- Parallel Programming (1)
- Parallel SAT solving (1)
- Parallel job execution time estimation (1)
- Paralleles Rechnen (1)
- Parallelrechner (1)
- Parameterized Complexity (1)
- Parametrisierte Komplexität (1)
- Parsing (1)
- Particle detector (1)
- Pedagogical issues (1)
- Pedestrian navigation (1)
- Peer-to-Peer-Netz ; GRID computing ; Zuverlässigkeit ; Web Services ; Betriebsmittelverwaltung ; Migration (1)
- Performance Evaluation (1)
- Performance Prediction (1)
- Personal Learning Environment (1)
- Personalization (1)
- Pervasive computing (1)
- Pervasive game (1)
- Pervasive learning (1)
- Phantoms (1)
- Planar tactile display (1)
- Planing (1)
- Plant identification (1)
- Platzierung (1)
- Polarization (1)
- Policy Enforcement (1)
- Power Monitoring (1)
- Prediction Game (1)
- Predictive Models (1)
- Privacy Protection (1)
- Probleme in der Studie (1)
- Process Management (1)
- Process model analysis (1)
- Process modeling (1)
- Product lifecycle management (1)
- Professoren (1)
- Programmierung (1)
- Programming (1)
- Programming by optimization (1)
- Proof Theory (1)
- Prototyping (1)
- Prozesse (1)
- Prozessmanagement (1)
- Prozessmodellierung (1)
- Prozesssynchronisierung (1)
- Prädiktionsspiel (1)
- Präferenzen (1)
- Quantified Boolean Formula (QBF) (1)
- Quantitative Modeling (1)
- Quantitative Modellierung (1)
- Queuing Theory (1)
- RADFET (1)
- RADFETs (1)
- REST (1)
- RSA triangle (1)
- Radiation hardness (1)
- Random access memory (1)
- Ranking (1)
- Reasoning (1)
- Reconfigurable (1)
- Region of Interest (1)
- Regression (1)
- Regularisierung (1)
- Regularization (1)
- Rekonfiguration (1)
- Reparatur (1)
- Reproducibility of results (1)
- Reversibility (1)
- SET pulsewidth distribution (1)
- SMT (SAT Modulo Theories) (1)
- SOA (1)
- SOA Security Pattern (1)
- STG decomposition (1)
- STG-Dekomposition (1)
- SWOT (1)
- Sample Selection Bias (1)
- Satisfiability (1)
- Scalability (1)
- Scale-invariant feature transform (SIFT) (1)
- Schlüsselkompetenzen (1)
- Schulmaterial (1)
- Scientific images (1)
- Screen reader (1)
- Seamless learning (1)
- Search problems (1)
- Security (1)
- Security Modelling (1)
- Segmentierung (1)
- Selektionsbias (1)
- Self-adaptive MPSoC (1)
- Semantic Interoperability (1)
- Semantic Search (1)
- Semantic data (1)
- Semantic web (1)
- Semantik Web (1)
- Semantische Suche (1)
- Semilinearity property (1)
- Sensornetzwerke (1)
- Sequence embeddings (1)
- Service Creation (1)
- Service Delivery Platform (1)
- Service convergence (1)
- Service orientation (1)
- Service-Orientierte Architekturen (1)
- Service-oriented Architecture (1)
- Service-oriented Architectures (1)
- Service-oriented architecture (1)
- Shader (1)
- Sharing (1)
- Sicherheitsmodellierung (1)
- Signal Processing (1)
- Signal processing (1)
- Signaling transduction networks (1)
- Signalquellentrennung (1)
- Signaltrennung (1)
- Simulation (1)
- Simulations (1)
- Simultane Diagonalisierung (1)
- Single Event Transient (1)
- Single Trial Analysis (1)
- Single event effect (1)
- Single event upsets (1)
- Single-event transient (SET) (1)
- Skelettberechnung (1)
- Social Media Analysis (1)
- Software-basierte Cache-Kohärenz (1)
- Sonnenteilchen-Ereignis (1)
- Spam (1)
- Spam Filtering (1)
- Spam-Erkennung (1)
- Spam-Filter (1)
- Spam-Filtering (1)
- Spatio-Spectral Filter (1)
- Spawning (1)
- Splicing (1)
- Splicing processor (1)
- Sprachdesign (1)
- Static Analysis (1)
- Statistical Tests (1)
- Statistical relational learning (1)
- Statistische Tests (1)
- Stilisierung (1)
- Stochastic relational process (1)
- Strahlungshartes Design (1)
- Strahlungshärte Entwurf (1)
- Stromverbrauchüberwachung (1)
- Strong equivalence (1)
- Structural equation modeling (1)
- Structuring (1)
- Strukturierung (1)
- Studentenerwartungen (1)
- Studentenhaltungen (1)
- Support Vectors (1)
- Support-Vector Lernen (1)
- Synthese (1)
- System Biologie (1)
- Systembiologie (1)
- Systems biology (1)
- Systems of parallel communicating (1)
- TMR (1)
- TPTP (1)
- Taktik (1)
- Telekommunikation (1)
- Temporal Answer Set Solving (1)
- Temporal Logic (1)
- Temporallogik (1)
- Temporäre Anbindung (1)
- Terminologische Logik (1)
- Texturen (1)
- Theoretischen Vorlesungen (1)
- Theory formation (1)
- Thermoelasticity (1)
- Time Augmented Petri Nets (1)
- Time Series Analysis (1)
- Time series (1)
- Tomography (1)
- Tool (1)
- Tools (1)
- Traceability (1)
- Traffic data (1)
- Transformation (1)
- Tree decomposition (1)
- Treewidth-aware reductions (1)
- Triple modular redundancy (TMR) (1)
- Tumor types (1)
- Turing machine (1)
- Type and effect systems (1)
- UAV imagery (1)
- UX (1)
- Ubiquitous learning (1)
- Ultrafast dynamics (1)
- Unabhängige Komponentenanalyse (1)
- Unary languages (1)
- Uniform Access Principle (1)
- University Service Bus (1)
- Universität Bagdad (1)
- Universität Potsdam (1)
- Universitätseinstellungen (1)
- Untere Schranken (1)
- Unterrichtswerkzeuge (1)
- Unvollständigkeit (1)
- Usability testing (1)
- Usage Interest (1)
- User submission pattern (1)
- User-centred design (1)
- VGG16 (1)
- VM (1)
- Value network (1)
- Verhalten (1)
- Verification (1)
- Verifikation (1)
- Verletzung Auflösung (1)
- Verletzung Erklärung (1)
- Verteiltes Rechnen (1)
- Verteilungsunterschied (1)
- Violation Explanation (1)
- Violation Resolution (1)
- Virtual reality (1)
- Virtuelles 3D Stadtmodell (1)
- Visual metaphor (1)
- Visualisierung (1)
- Vorhersagemodelle (1)
- Wahrnehmung (1)
- Wahrnehmung von Arousal (1)
- Wahrnehmungsunterschiede (1)
- Warteschlangentheorie (1)
- Web Services (1)
- Web Sites (1)
- Web of Data (1)
- Webseite (1)
- Well-structuredness (1)
- Wetterextreme (1)
- Wireless Sensor Networks (1)
- Wirtschaftsinformatik (1)
- Wissen (1)
- Wissenschaftlichesworkflows (1)
- Wissensmanagement (1)
- Wissensrepräsentation und -verarbeitung (1)
- Wissensrepräsentation und Schlussfolgerung (1)
- Wohlstrukturiertheit (1)
- Word embeddings (1)
- Workflow (1)
- X-masking (1)
- X-ray computed (1)
- X-values (1)
- ZQSA (1)
- ZQSAT (1)
- Zeitbehaftete Petri Netze (1)
- Zero-Suppressed Binary Decision Diagram (ZDD) (1)
- Zuverlässigkeitsanalyse (1)
- abstraction (1)
- accepting grammars (1)
- action and change (1)
- activities (1)
- activity (1)
- acute liver failure (1)
- acyclicity properties (1)
- adaptiv (1)
- adaptive (1)
- adversarial classification (1)
- algorithm configuration (1)
- algorithm schedules (1)
- algorithm scheduling (1)
- algorithm selection (1)
- algorithms (1)
- analysis (1)
- anisotropic Kuwahara filter (1)
- annealing (1)
- anxiety (1)
- approximate joint diagonalization (1)
- approximate model counting (1)
- architecture (1)
- argumentation (1)
- argumentation structure (1)
- arithmethische Prozeduren (1)
- arithmetic procedures (1)
- arousal (1)
- arousal perception (1)
- artificial intelligence (1)
- artistic rendering (1)
- asynchronous circuit (1)
- asynchrounous design (1)
- authentication (1)
- autism (1)
- automata (1)
- automated driving (1)
- automated guided vehicle routing (1)
- automated planning (1)
- automatic theorem prover (1)
- automatisierter Theorembeweiser (1)
- behavioral (1)
- behavioral abstraction (1)
- belief merging (1)
- belief revision (1)
- benchmark (1)
- bibliometric analysis (1)
- bild (1)
- biometrics (1)
- biometrische Identifikation (1)
- blind source separation (1)
- block representation (1)
- bootstrapping (1)
- brain-computer interface (1)
- building models (1)
- bundled data (1)
- business informatics (1)
- camera sensor (1)
- car assembly operations (1)
- cartographic design (1)
- cellular automata (1)
- changing the study field (1)
- changing the university (1)
- choreographies (1)
- circuit Faults (1)
- citation analysis (1)
- classifier calibration (1)
- classroom material (1)
- click controller (1)
- climate change (1)
- climate impact analysis (1)
- clocks (1)
- clustering (1)
- co-citation analysis (1)
- co-occurrence analysis (1)
- code generation (1)
- coherence relation (1)
- coherence-enhancing filtering (1)
- collaborative learning (1)
- combinatorial optimization problems (1)
- combined task and motion planning (1)
- common spatial patterns (1)
- communication (1)
- competition (1)
- complex networks (1)
- complexity (1)
- compliance (1)
- computational biology (1)
- computational methods (1)
- computational thinking (1)
- computer graphics (1)
- computer security (1)
- computer vision (1)
- computergestützte Methoden (1)
- concession (1)
- conductive argument (1)
- connection calculus (1)
- connective (1)
- connectivity (1)
- consistency (1)
- consistency checking (1)
- consistency measures (1)
- constraints (1)
- context-free grammar (1)
- context-sensitive (1)
- continuous (1)
- contrast (1)
- controlled vocabularies (1)
- corpus analysis (1)
- correlated errors (1)
- course timetabling (1)
- craters (1)
- crop (1)
- decidability questions (1)
- decision trees (1)
- declarative problem solving (1)
- deep learning (1)
- deep residual networks (1)
- degree of formality (1)
- degree of non-context-freeness (1)
- degree of non-regularity (1)
- degree of non-regulation (1)
- depression (1)
- design flow (1)
- design principles (1)
- determinism (1)
- detrending (1)
- developmental systems (1)
- diagnosis (1)
- didaktische Rekonstruktion (1)
- difference of Gaussians (1)
- digital circuit (1)
- digital design (1)
- digitally-enabled pedagogies (1)
- domain-specific APIs (1)
- dropout (1)
- drug discovery (1)
- dynamic (1)
- dynamic classification (1)
- dynamic reconfiguration (1)
- dynamic service binding (1)
- dynamisch (1)
- dynamische Klassifikation (1)
- e-Learning (1)
- e-learning (1)
- eLectures (1)
- economic ripples (1)
- education (1)
- educational reconstruction (1)
- educational systems (1)
- educational timetabling (1)
- eingebettete Systeme (1)
- einseitige Kommunikation (1)
- email spam detection (1)
- emission factor (1)
- emotion (1)
- emotion representation (1)
- emotion research (1)
- endothelin (1)
- endothelin-converting enzyme (1)
- ensemble kalman filter (1)
- ensemble methods (1)
- entity alignment (1)
- epistemic logic programs (1)
- epistemic specifications (1)
- equality (1)
- error propagation (1)
- evaluation (1)
- event-related desynchronization (1)
- evidence theory (1)
- evolution (1)
- explicit negation (1)
- external ambiguity (1)
- external memory algorithms (1)
- extreme weather (1)
- eye movements (1)
- fading (1)
- fault tolerance (1)
- field-programmable gate array (1)
- finite model computation (1)
- finite state sequential transducers (1)
- flow-based bilateral filter (1)
- formal (1)
- formal argumentation systems (1)
- formalism (1)
- functions (1)
- gait (1)
- gap-filling (1)
- generalization (1)
- geometry generation (1)
- geospatial data (1)
- geospatial services (1)
- gradient boosting (1)
- grammar (1)
- graph analysis (1)
- graph clustering (1)
- greenhouse gas (1)
- hardware accelerator (1)
- hardware architecture (1)
- hardware design (1)
- high-throughput analysis (1)
- human computer interaction (1)
- hybrid (1)
- hybrid solving (1)
- hybrides Problemlösen (1)
- ice harboring (1)
- image (1)
- image classification (1)
- image data analysis (1)
- image recognition (1)
- imaging (1)
- impacts (1)
- incompleteness (1)
- inconsistency (1)
- incremental SVM (1)
- independent component analysis (1)
- indirect economic impacts (1)
- indirekte ökonomische Effekte (1)
- informal and formal learning (1)
- informal logic (1)
- information flow control (1)
- informatische Bildung im Sekundarbereich (1)
- input accuracy (1)
- interaction modeling (1)
- internal ambiguity (1)
- intrusion detection (1)
- irradiation (1)
- joint lab (1)
- kernel PCA (1)
- kernel methods (1)
- key competences in physical computing (1)
- kidney cancer (1)
- knowledge representation and nonmonotonic reasoning (1)
- knowledge representation and reasoning (1)
- konvergente Dienste (1)
- landmarks (1)
- language design (1)
- latches (1)
- leanCoP (1)
- leftmost derivations (1)
- linear programming (1)
- locomotion (1)
- logic (1)
- logic synthesis (1)
- logic-based modeling (1)
- logical signaling networks (1)
- logische Programmierung (1)
- logische Signalnetzwerke (1)
- loop formulas (1)
- loose programming (1)
- loss propagation (1)
- lunar exploration (1)
- machine learning algorithms (1)
- macro-economic modelling (1)
- makroökonomische Modellierung (1)
- malware detection (1)
- manipulation planning (1)
- map/reduce (1)
- maschninelles Lernen (1)
- mathematics education (1)
- measure development (1)
- media (1)
- medical (1)
- medizinisch (1)
- metabolic network (1)
- metabolism (1)
- metabolomics (1)
- metadata (1)
- metastasis (1)
- middleware (1)
- mixture models (1)
- mobile devices (1)
- mobile learning (1)
- mobile technologies and apps (1)
- molecular networks (1)
- molekulare Netzwerke (1)
- multi-class classification (1)
- natural disasters (1)
- natural language generation (1)
- neighborhood (1)
- networks-on-chip (1)
- neural networks (1)
- neutral endopeptidase (1)
- nichtlineare ICA (1)
- nichtlineare PCA (NLPCA) (1)
- non-monotonic reasoning (1)
- nonlinear ICA (1)
- nonlinear PCA (NLPCA) (1)
- nonphotorealistic rendering (NPR) (1)
- o-ambiguity (1)
- objective difficulty (1)
- omega (1)
- on-farm evaluation (1)
- one-sided communication (1)
- oneM2M (1)
- oneM2M Ontology (1)
- ontologies (1)
- organisational evolution (1)
- outlier detection (1)
- output space compaction (1)
- overcomplete ICA (1)
- pMOS radiation dosimeter (1)
- paper prototyping (1)
- parallel processing (1)
- parallel programming (1)
- parallel rewriting (1)
- parallel solving (1)
- parallele Programmierung (1)
- paralleles Lösen (1)
- parity aggregate operator (1)
- pattern recognition (1)
- pdf forms (1)
- philosophy of mathematics (1)
- physical Computing (1)
- physical computing tools (1)
- placement (1)
- planning (1)
- plug-ins (1)
- portfolio-based solving (1)
- prediction (1)
- predictive models (1)
- preferences (1)
- premise acceptability (1)
- priorities (1)
- probabilistic deep learning (1)
- probabilistic deep metric learning (1)
- probabilistische tiefe neuronale Netze (1)
- probabilistisches tiefes metrisches Lernen (1)
- process (1)
- process model alignment (1)
- process modeling (1)
- process synchronization (1)
- professors (1)
- program encodings (1)
- programmed grammars (1)
- projection (1)
- proof (1)
- proof assistant (1)
- proof complexity (1)
- proof environment (1)
- propagation probability (1)
- pruritus (1)
- pulse stretching inverters (1)
- quality of life (1)
- quantum (1)
- radiation hardness (1)
- radiation hardness design (1)
- random forest (1)
- real arguments (1)
- real-time (1)
- real-time application (1)
- real-time mapping (1)
- real-walking (1)
- reconfiguration (1)
- reference (1)
- referential effectiveness (1)
- regression (1)
- regular language (1)
- rekonfigurierbar (1)
- relevance (1)
- reliability analysis (1)
- reliability assessment (1)
- repair (1)
- resources (1)
- restricted parallelism (1)
- risk analysis (1)
- robust ICA (1)
- robuste ICA (1)
- safety (1)
- satisfiability (1)
- scheduling (1)
- secondary computer science education (1)
- segmentation (1)
- selbstanpassendes Multiprozessorsystem (1)
- selective fault tolerance (1)
- self-checking (1)
- semantic domain modeling (1)
- semantic web (1)
- semantische Domänenmodellierung (1)
- sensitivity (1)
- service composition (1)
- shader (1)
- simplicity (1)
- single event upsets (1)
- single-event transient (1)
- single-trial-analysis (1)
- site-specific weed management (1)
- skeletonization (1)
- sleep quality (1)
- smart farming (1)
- smartphone (1)
- soft errors (1)
- software-based cache coherence (1)
- space missions (1)
- speed independence (1)
- stable model semantics (1)
- state complexity (1)
- static analysis (1)
- static prediction games (1)
- strahleninduzierte Einzelereignis-Effekte (1)
- strong equivalence (1)
- structured output prediction (1)
- strukturierte Vorhersage (1)
- study problems (1)
- stylization (1)
- sufficiency (1)
- suicidal ideations (1)
- supply chains (1)
- support vector machines (1)
- tableau calculi (1)
- tactic (1)
- teachers (1)
- teaching (1)
- technical notes and rapid communications (1)
- tele-teaching (1)
- temporary binding (1)
- terrain models (1)
- test (1)
- test response compaction (1)
- textures (1)
- theory of computation (1)
- timing (1)
- tools (1)
- tools for teaching (1)
- topics (1)
- touch input (1)
- tptp (1)
- transformation (1)
- transient Faults (1)
- transient analysis (1)
- triangulated irregular networks (1)
- triple modular redundancy (1)
- tutorial section (1)
- unfounded sets (1)
- user experience (1)
- video annotation (1)
- virtual 3D city model (1)
- virtual 3D city models (1)
- virtual machine (1)
- virtuelle 3D-Stadtmodelle (1)
- visualization (1)
- weather extremes (1)
- wheat crops (1)
- work productivity (1)
- workflow management (1)
- yellow rust (1)
- zero-aliasing (1)
- überbestimmte ICA (1)
Institute
- Institut für Informatik und Computational Science (793)
- Hasso-Plattner-Institut für Digital Engineering gGmbH (16)
- Extern (4)
- Institut für Physik und Astronomie (2)
- Department Erziehungswissenschaft (1)
- Department Linguistik (1)
- Institut für Biochemie und Biologie (1)
- Potsdam Institute for Climate Impact Research (PIK) e. V. (1)
- Wirtschaftswissenschaften (1)
A distinguishing feature of Answer Set Programming is that all atoms belonging to a stable model must be founded. That is, an atom must not only be true but provably true. This can be made precise by means of the constructive logic of Here-and-There, whose equilibrium models correspond to stable models. One way of looking at foundedness is to regard Boolean truth values as ordered by letting true be greater than false. Then, each Boolean variable takes the smallest truth value that can be proven for it. This idea was generalized by Aziz to ordered domains and applied to constraint satisfaction problems. As before, the idea is that a, say integer, variable gets only assigned to the smallest integer that can be justified. In this paper, we present a logical reconstruction of Aziz’ idea in the setting of the logic of Here-and-There. More precisely, we start by defining the logic of Here-and-There with lower bound founded variables along with its equilibrium models and elaborate upon its formal properties. Finally, we compare our approach with related ones and sketch future work.
We introduce a type and effect system, for an imperative object calculus, which infers sharing possibly introduced by the evaluation of an expression, represented as an equivalence relation among its free variables. This direct representation of sharing effects at the syntactic level allows us to express in a natural way, and to generalize, widely-used notions in literature, notably uniqueness and borrowing. Moreover, the calculus is pure in the sense that reduction is defined on language terms only, since they directly encode store. The advantage of this non-standard execution model with respect to a behaviorally equivalent standard model using a global auxiliary structure is that reachability relations among references are partly encoded by scoping. (C) 2018 Elsevier B.V. All rights reserved.
teaspoon
(2018)
Answer Set Programming (ASP) is an approach to declarative problem solving, combining a rich yet simple modeling language with high performance solving capacities. We here develop an ASP-based approach to curriculum-based course timetabling (CB-CTT), one of the most widely studied course timetabling problems. The resulting teaspoon system reads a CB-CTT instance of a standard input format and converts it into a set of ASP facts. In turn, these facts are combined with a first-order encoding for CB-CTT solving, which can subsequently be solved by any off-the-shelf ASP systems. We establish the competitiveness of our approach by empirically contrasting it to the best known bounds obtained so far via dedicated implementations. Furthermore, we extend the teaspoon system to multi-objective course timetabling and consider minimal perturbation problems.
plasp 3
(2019)
We describe the new version of the Planning Domain Definition Language (PDDL)-to-Answer Set Programming (ASP) translator plasp. First, it widens the range of accepted PDDL features. Second, it contains novel planning encodings, some inspired by Satisfiability Testing (SAT) planning and others exploiting ASP features such as well-foundedness. All of them are designed for handling multivalued fluents in order to capture both PDDL as well as SAS planning formats. Third, enabled by multishot ASP solving, it offers advanced planning algorithms also borrowed from SAT planning. As a result, plasp provides us with an ASP-based framework for studying a variety of planning techniques in a uniform setting. Finally, we demonstrate in an empirical analysis that these techniques have a significant impact on the performance of ASP planning.
The Surface Water and Ocean Topography (SWOT) mission is a next generation satellite mission expected to provide a 2 km-resolution observation of the sea surface height (SSH) on a two-dimensional swath. Processing SWOT data will be challenging because of the large amount of data, the mismatch between a high spatial resolution and a low temporal resolution, and the observation errors. The present paper focuses on the reduction of the spatially structured errors of SWOT SSH data. It investigates a new error reduction method and assesses its performance in an observing system simulation experiment. The proposed error-reduction method first projects the SWOT SSH onto a subspace spanned by the SWOT spatially structured errors. This projection is removed from the SWOT SSH to obtain a detrended SSH. The detrended SSH is then processed within an ensemble data assimilation analysis to retrieve a full SSH field. In the latter step, the detrending is applied to both the SWOT data and an ensemble of model-simulated SSH fields. Numerical experiments are performed with synthetic SWOT observations and an ensemble from a North Atlantic, 1/60 degrees simulation of the ocean circulation (NATL60). The data assimilation analysis is carried out with an ensemble Kalman filter. The results are assessed with root mean square errors, power spectrum density, and spatial coherence. They show that a significant part of the large scale SWOT errors is reduced. The filter analysis also reduces the small scale errors and allows for an accurate recovery of the energy of the signal down to 25 km scales. In addition, using the SWOT nadir data to adjust the SSH detrending further reduces the errors.
A common feature in Answer Set Programming is the use of a second negation, stronger than default negation and sometimes called explicit, strong or classical negation. This explicit negation is normally used in front of atoms, rather than allowing its use as a regular operator. In this paper we consider the arbitrary combination of explicit negation with nested expressions, as those defined by Lifschitz, Tang and Turner. We extend the concept of reduct for this new syntax and then prove that it can be captured by an extension of Equilibrium Logic with this second negation. We study some properties of this variant and compare to the already known combination of Equilibrium Logic with Nelson's strong negation.
The target article discusses the question of how educational makerspaces can become places supportive of knowledge construction. This question is too often neglected by people who run makerspaces, as they mostly explain how to use different tools and focus on the creation of a product. In makerspaces, often pupils also engage in physical computing activities and thus in the creation of interactive artifacts containing embedded systems, such as smart shoes or wristbands, plant monitoring systems or drink mixing machines. This offers the opportunity to reflect on teaching physical computing in computer science education, where similarly often the creation of the product is so strongly focused upon that the reflection of the learning process is pushed into the background.
MUP
(2020)
Message Queuing Telemetry Transport (MQTT) is one of the dominating protocols for edge- and cloud-based Internet of Things (IoT) solutions. When a security vulnerability of an IoT device is known, it has to be fixed as soon as possible. This requires a firmware update procedure. In this paper, we propose a secure update protocol for MQTT-connected devices which ensures the freshness of the firmware, authenticates the new firmware and considers constrained devices. We show that the update protocol is easy to integrate in an MQTT-based IoT network using a semantic approach. The feasibility of our approach is demonstrated by a detailed performance analysis of our prototype implementation on a IoT device with 32 kB RAM. Thereby, we identify design issues in MQTT 5 which can help to improve the support of constrained devices.
MUP
(2020)
Message Queuing Telemetry Transport (MQTT) is one of the dominating protocols for edge- and cloud-based Internet of Things (IoT) solutions. When a security vulnerability of an IoT device is known, it has to be fixed as soon as possible. This requires a firmware update procedure. In this paper, we propose a secure update protocol for MQTT-connected devices which ensures the freshness of the firmware, authenticates the new firmware and considers constrained devices. We show that the update protocol is easy to integrate in an MQTT-based IoT network using a semantic approach. The feasibility of our approach is demonstrated by a detailed performance analysis of our prototype implementation on a IoT device with 32 kB RAM. Thereby, we identify design issues in MQTT 5 which can help to improve the support of constrained devices.
In a recent line of research, two familiar concepts from logic programming semantics (unfounded sets and splitting) were extrapolated to the case of epistemic logic programs. The property of epistemic splitting provides a natural and modular way to understand programs without epistemic cycles but, surprisingly, was only fulfilled by Gelfond's original semantics (G91), among the many proposals in the literature. On the other hand, G91 may suffer from a kind of self-supported, unfounded derivations when epistemic cycles come into play. Recently, the absence of these derivations was also formalised as a property of epistemic semantics called foundedness. Moreover, a first semantics proved to satisfy foundedness was also proposed, the so-called Founded Autoepistemic Equilibrium Logic (FAEEL). In this paper, we prove that FAEEL also satisfies the epistemic splitting property something that, together with foundedness, was not fulfilled by any other approach up to date. To prove this result, we provide an alternative characterisation of FAEEL as a combination of G91 with a simpler logic we called Founded Epistemic Equilibrium Logic (FEEL), which is somehow an extrapolation of the stable model semantics to the modal logic S5.
Parsing of argumentative structures has become a very active line of research in recent years. Like discourse parsing or any other natural language task that requires prediction of linguistic structures, most approaches choose to learn a local model and then perform global decoding over the local probability distributions, often imposing constraints that are specific to the task at hand. Specifically for argumentation parsing, two decoding approaches have been recently proposed: Minimum Spanning Trees (MST) and Integer Linear Programming (ILP), following similar trends in discourse parsing. In contrast to discourse parsing though, where trees are not always used as underlying annotation schemes, argumentation structures so far have always been represented with trees. Using the 'argumentative microtext corpus' [in: Argumentation and Reasoned Action: Proceedings of the 1st European Conference on Argumentation, Lisbon 2015 / Vol. 2, College Publications, London, 2016, pp. 801-815] as underlying data and replicating three different decoding mechanisms, in this paper we propose a novel ILP decoder and an extension to our earlier MST work, and then thoroughly compare the approaches. The result is that our new decoder outperforms related work in important respects, and that in general, ILP and MST yield very similar performance.
Flux-P
(2012)
Quantitative knowledge of intracellular fluxes in metabolic networks is invaluable for inferring metabolic system behavior and the design principles of biological systems. However, intracellular reaction rates can not often be calculated directly but have to be estimated; for instance, via 13C-based metabolic flux analysis, a model-based interpretation of stable carbon isotope patterns in intermediates of metabolism. Existing software such as FiatFlux, OpenFLUX or 13CFLUX supports experts in this complex analysis, but requires several steps that have to be carried out manually, hence restricting the use of this software for data interpretation to a rather small number of experiments. In this paper, we present Flux-P as an approach to automate and standardize 13C-based metabolic flux analysis, using the Bio-jETI workflow framework. Exemplarily based on the FiatFlux software, it demonstrates how services can be created that carry out the different analysis steps autonomously and how these can subsequently be assembled into software workflows that perform automated, high-throughput intracellular flux analysis of high quality and reproducibility. Besides significant acceleration and standardization of the data analysis, the agile workflow-based realization supports flexible changes of the analysis workflows on the user level, making it easy to perform custom analyses.
Answer Set Programming (ASP) has become a popular and widespread paradigm for practical Knowledge Representation thanks to its expressiveness and the available enhancements of its input language. One of such enhancements is the use of aggregates, for which different semantic proposals have been made. In this paper, we show that any ASP aggregate interpreted under Gelfond and Zhang's (GZ) semantics can be replaced (under strong equivalence) by a propositional formula. Restricted to the original GZ syntax, the resulting formula is reducible to a disjunction of conjunctions of literals but the formulation is still applicable even when the syntax is extended to allow for arbitrary formulas (including nested aggregates) in the condition. Once GZ-aggregates are represented as formulas, we establish a formal comparison (in terms of the logic of Here-and-There) to Ferraris' (F) aggregates, which are defined by a different formula translation involving nested implications. In particular, we prove that if we replace an F-aggregate by a GZ-aggregate in a rule head, we do not lose answer sets (although more can be gained). This extends the previously known result that the opposite happens in rule bodies, i.e., replacing a GZ-aggregate by an F-aggregate in the body may yield more answer sets. Finally, we characterize a class of aggregates for which GZ- and F-semantics coincide.
Detection of malware-infected computers and detection of malicious web domains based on their encrypted HTTPS traffic are challenging problems, because only addresses, timestamps, and data volumes are observable. The detection problems are coupled, because infected clients tend to interact with malicious domains. Traffic data can be collected at a large scale, and antivirus tools can be used to identify infected clients in retrospect. Domains, by contrast, have to be labeled individually after forensic analysis. We explore transfer learning based on sluice networks; this allows the detection models to bootstrap each other. In a large-scale experimental study, we find that the model outperforms known reference models and detects previously unknown malware, previously unknown malware families, and previously unknown malicious domains.
TrainTrap
(2020)
In this work we tackle the problem of checking strong equivalence of logic programs that may contain local auxiliary atoms, to be removed from their stable models and to be forbidden in any external context. We call this property projective strong equivalence (PSE). It has been recently proved that not any logic program containing auxiliary atoms can be reformulated, under PSE, as another logic program or formula without them – this is known as strongly persistent forgetting. In this paper, we introduce a conservative extension of Equilibrium Logic and its monotonic basis, the logic of Here-and-There, in which we deal with a new connective ‘|’ we call fork. We provide a semantic characterisation of PSE for forks and use it to show that, in this extension, it is always possible to forget auxiliary atoms under strong persistence. We further define when the obtained fork is representable as a regular formula.
Multi-sided platforms (MSP) strongly affect markets and play a crucial part within the digital and networked economy. Although empirical evidence indicates their occurrence in many industries, research has not investigated the game-changing impact of MSP on traditional markets to a sufficient extent. More specifically, we have little knowledge of how MSP affect value creation and customer interaction in entire markets, exploiting the potential of digital technologies to offer new value propositions. Our paper addresses this research gap and provides an initial systematic approach to analyze the impact of MSP on the insurance industry. For this purpose, we analyze the state of the art in research and practice in order to develop a reference model of the value network for the insurance industry. On this basis, we conduct a case-study analysis to discover and analyze roles which are occupied or even newly created by MSP. As a final step, we categorize MSP with regard to their relation to traditional insurance companies, resulting in a classification scheme with four MSP standard types: Competition, Coordination, Cooperation, Collaboration.
Background: The biological interpretation of large-scale gene expression data is one of the paramount challenges in current bioinformatics. In particular, placing the results in the context of other available functional genomics data, such as existing bio-ontologies, has already provided substantial improvement for detecting and categorizing genes of interest. One common approach is to look for functional annotations that are significantly enriched within a group or cluster of genes, as compared to a reference group. Results: In this work, we suggest the information-theoretic concept of mutual information to investigate the relationship between groups of genes, as given by data-driven clustering, and their respective functional categories. Drawing upon related approaches (Gibbons and Roth, Genome Research 12: 1574-1581, 2002), we seek to quantify to what extent individual attributes are sufficient to characterize a given group or cluster of genes. Conclusion: We show that the mutual information provides a systematic framework to assess the relationship between groups or clusters of genes and their functional annotations in a quantitative way. Within this framework, the mutual information allows us to address and incorporate several important issues, such as the interdependence of functional annotations and combinatorial combinations of attributes. It thus supplements and extends the conventional search for overrepresented attributes within a group or cluster of genes. In particular taking combinations of attributes into account, the mutual information opens the way to uncover specific functional descriptions of a group of genes or clustering result. All datasets and functional annotations used in this study are publicly available. All scripts used in the analysis are provided as additional files.
Incremental Support Vector Machines (SVM) are instrumental in practical applications of online learning. This work focuses on the design and analysis of efficient incremental SVM learning, with the aim of providing a fast, numerically stable and robust implementation. A detailed analysis of convergence and of algorithmic complexity of incremental SVM learning is carried out. Based on this analysis, a new design of storage and numerical operations is proposed, which speeds up the training of an incremental SVM by a factor of 5 to 20. The performance of the new algorithm is demonstrated in two scenarios: learning with limited resources and active learning. Various applications of the algorithm, such as in drug discovery, online monitoring of industrial devices and and surveillance of network traffic, can be foreseen.
A central insight from psychological studies on human eye movements is that eye movement patterns are highly individually characteristic. They can, therefore, be used as a biometric feature, that is, subjects can be identified based on their eye movements. This thesis introduces new machine learning methods to identify subjects based on their eye movements while viewing arbitrary content. The thesis focuses on probabilistic modeling of the problem, which has yielded the best results in the most recent literature. The thesis studies the problem in three phases by proposing a purely probabilistic, probabilistic deep learning, and probabilistic deep metric learning approach. In the first phase, the thesis studies models that rely on psychological concepts about eye movements. Recent literature illustrates that individual-specific distributions of gaze patterns can be used to accurately identify individuals. In these studies, models were based on a simple parametric family of distributions. Such simple parametric models can be robustly estimated from sparse data, but have limited flexibility to capture the differences between individuals. Therefore, this thesis proposes a semiparametric model of gaze patterns that is flexible yet robust for individual identification. These patterns can be understood as domain knowledge derived from psychological literature. Fixations and saccades are examples of simple gaze patterns. The proposed semiparametric densities are drawn under a Gaussian process prior centered at a simple parametric distribution. Thus, the model will stay close to the parametric class of densities if little data is available, but it can also deviate from this class if enough data is available, increasing the flexibility of the model. The proposed method is evaluated on a large-scale dataset, showing significant improvements over the state-of-the-art. Later, the thesis replaces the model based on gaze patterns derived from psychological concepts with a deep neural network that can learn more informative and complex patterns from raw eye movement data. As previous work has shown that the distribution of these patterns across a sequence is informative, a novel statistical aggregation layer called the quantile layer is introduced. It explicitly fits the distribution of deep patterns learned directly from the raw eye movement data. The proposed deep learning approach is end-to-end learnable, such that the deep model learns to extract informative, short local patterns while the quantile layer learns to approximate the distributions of these patterns. Quantile layers are a generic approach that can converge to standard pooling layers or have a more detailed description of the features being pooled, depending on the problem. The proposed model is evaluated in a large-scale study using the eye movements of subjects viewing arbitrary visual input. The model improves upon the standard pooling layers and other statistical aggregation layers proposed in the literature. It also improves upon the state-of-the-art eye movement biometrics by a wide margin. Finally, for the model to identify any subject — not just the set of subjects it is trained on — a metric learning approach is developed. Metric learning learns a distance function over instances. The metric learning model maps the instances into a metric space, where sequences of the same individual are close, and sequences of different individuals are further apart. This thesis introduces a deep metric learning approach with distributional embeddings. The approach represents sequences as a set of continuous distributions in a metric space; to achieve this, a new loss function based on Wasserstein distances is introduced. The proposed method is evaluated on multiple domains besides eye movement biometrics. This approach outperforms the state of the art in deep metric learning in several domains while also outperforming the state of the art in eye movement biometrics.
Combined optimization of spatial and temporal filters for improving brain-computer interfacing
(2006)
Brain-computer interface (BCI) systems create a novel communication channel from the brain to an output de ice by bypassing conventional motor output pathways of nerves and muscles. Therefore they could provide a new communication and control option for paralyzed patients. Modern BCI technology is essentially based on techniques for the classification of single-trial brain signals. Here we present a novel technique that allows the simultaneous optimization of a spatial and a spectral filter enhancing discriminability rates of multichannel EEG single-trials. The evaluation of 60 experiments involving 22 different subjects demonstrates the significant superiority of the proposed algorithm over to its classical counterpart: the median classification error rate was decreased by 11%. Apart from the enhanced classification, the spatial and/or the spectral filter that are determined by the algorithm can also be used for further analysis of the data, e.g., for source localization of the respective brain rhythms.
We consider generating and accepting programmed grammars with bounded degree of non-regulation, that is, the maximum number of elements in success or in failure fields of the underlying grammar. In particular, it is shown that this measure can be restricted to two without loss of descriptional capacity, regardless of whether arbitrary derivations or left-most derivations are considered. Moreover, in some cases, precise characterizations of the linear bounded automaton problem in terms of programmed grammars are obtained. Thus, the results presented in this paper shed new light on some longstanding open problem in the theory of computational complexity.
Emotions are a central element of human experience. They occur with high frequency in everyday life and play an important role in decision making. However, currently there is no consensus among researchers on what constitutes an emotion and on how emotions should be investigated. This dissertation identifies three problems of current emotion research: the problem of ground truth, the problem of incomplete constructs and the problem of optimal representation. I argue for a focus on the detailed measurement of emotion manifestations with computer-aided methods to solve these problems. This approach is demonstrated in three research projects, which describe the development of methods specific to these problems as well as their application to concrete research questions.
The problem of ground truth describes the practice to presuppose a certain structure of emotions as the a priori ground truth. This determines the range of emotion descriptions and sets a standard for the correct assignment of these descriptions. The first project illustrates how this problem can be circumvented with a multidimensional emotion perception paradigm which stands in contrast to the emotion recognition paradigm typically employed in emotion research. This paradigm allows to calculate an objective difficulty measure and to collect subjective difficulty ratings for the perception of emotional stimuli. Moreover, it enables the use of an arbitrary number of emotion stimuli categories as compared to the commonly used six basic emotion categories. Accordingly, we collected data from 441 participants using dynamic facial expression stimuli from 40 emotion categories. Our findings suggest an increase in emotion perception difficulty with increasing actor age and provide evidence to suggest that young adults, the elderly and men underestimate their emotion perception difficulty. While these effects were predicted from the literature, we also found unexpected and novel results. In particular, the increased difficulty on the objective difficulty measure for female actors and observers stood in contrast to reported findings. Exploratory analyses revealed low relevance of person-specific variables for the prediction of emotion perception difficulty, but highlighted the importance of a general pleasure dimension for the ease of emotion perception.
The second project targets the problem of incomplete constructs which relates to vaguely defined psychological constructs on emotion with insufficient ties to tangible manifestations. The project exemplifies how a modern data collection method such as face tracking data can be used to sharpen these constructs on the example of arousal, a long-standing but fuzzy construct in emotion research. It describes how measures of distance, speed and magnitude of acceleration can be computed from face tracking data and investigates their intercorrelations. We find moderate to strong correlations among all measures of static information on one hand and all measures of dynamic information on the other. The project then investigates how self-rated arousal is tied to these measures in 401 neurotypical individuals and 19 individuals with autism. Distance to the neutral face was predictive of arousal ratings in both groups. Lower mean arousal ratings were found for the autistic group, but no difference in correlation of the measures and arousal ratings could be found between groups. Results were replicated in a high autistic traits group consisting of 41 participants. The findings suggest a qualitatively similar perception of arousal for individuals with and without autism. No correlations between valence ratings and any of the measures could be found which emphasizes the specificity of our tested measures for the construct of arousal.
The problem of optimal representation refers to the search for the best representation of emotions and the assumption that there is a one-fits-all solution. In the third project we introduce partial least squares analysis as a general method to find an optimal representation to relate two high-dimensional data sets to each other. The project demonstrates its applicability to emotion research on the question of emotion perception differences between men and women. The method was used with emotion rating data from 441 participants and face tracking data computed on 306 videos. We found quantitative as well as qualitative differences in the perception of emotional facial expressions between these groups. We showed that women’s emotional perception systematically captured more of the variance in facial expressions. Additionally, we could show that significant differences exist in the way that women and men perceive some facial expressions which could be visualized as concrete facial expression sequences. These expressions suggest differing perceptions of masked and ambiguous facial expressions between the sexes. In order to facilitate use of the developed method by the research community, a package for the statistical environment R was written. Furthermore, to call attention to the method and its usefulness for emotion research, a website was designed that allows users to explore a model of emotion ratings and facial expression data in an interactive fashion.
Iterated finite state sequential transducers are considered as language generating devices. The hierarchy induced by the size of the state alphabet is proved to collapse to the fourth level. The corresponding language families are related to the families of languages generated by Lindenmayer systems and Chomsky grammars. Finally, some results on deterministic and extended iterated finite state transducers are established.
PLATON
(2019)
Lesson planning is both an important and demanding task—especially as part of teacher training. This paper presents the requirements for a lesson planning system and evaluates existing systems regarding these requirements. One major drawback of existing software tools is that most are limited to a text- or form-based representation of the lesson designs. In this article, a new approach with a graphical, time-based representation with (automatic) analyses methods is proposed and the system architecture and domain model are described in detail. The approach is implemented in an interactive, web-based prototype called PLATON, which additionally supports the management of lessons in units as well as the modelling of teacher and student-generated resources. The prototype was evaluated in a study with 61 prospective teachers (bachelor’s and master’s preservice teachers as well as teacher trainees in post-university teacher training) in Berlin, Germany, with a focus on usability. The results show that this approach proofed usable for lesson planning and offers positive effects for the perception of time and self-reflection.
PLATON
(2019)
Lesson planning is both an important and demanding task—especially as part of teacher training. This paper presents the requirements for a lesson planning system and evaluates existing systems regarding these requirements. One major drawback of existing software tools is that most are limited to a text- or form-based representation of the lesson designs. In this article, a new approach with a graphical, time-based representation with (automatic) analyses methods is proposed and the system architecture and domain model are described in detail. The approach is implemented in an interactive, web-based prototype called PLATON, which additionally supports the management of lessons in units as well as the modelling of teacher and student-generated resources. The prototype was evaluated in a study with 61 prospective teachers (bachelor’s and master’s preservice teachers as well as teacher trainees in post-university teacher training) in Berlin, Germany, with a focus on usability. The results show that this approach proofed usable for lesson planning and offers positive effects for the perception of time and self-reflection.
The usage of mobile devices is rapidly growing with Android being the most prevalent mobile operating system. Thanks to the vast variety of mobile applications, users are preferring smartphones over desktops for day to day tasks like Internet surfing. Consequently, smartphones store a plenitude of sensitive data. This data together with the high values of smartphones make them an attractive target for device/data theft (thieves/malicious applications).
Unfortunately, state-of-the-art anti-theft solutions do not work if they do not have an active network connection, e.g., if the SIM card was removed from the device. In the majority of these cases, device owners permanently lose their smartphone together with their personal data, which is even worse.
Apart from that malevolent applications perform malicious activities to steal sensitive information from smartphones. Recent research considered static program analysis to detect dangerous data leaks. These analyses work well for data leaks due to inter-component communication, but suffer from shortcomings for inter-app communication with respect to precision, soundness, and scalability.
This thesis focuses on enhancing users' privacy on Android against physical device loss/theft and (un)intentional data leaks. It presents three novel frameworks: (1) ThiefTrap, an anti-theft framework for Android, (2) IIFA, a modular inter-app intent information flow analysis of Android applications, and (3) PIAnalyzer, a precise approach for PendingIntent vulnerability analysis.
ThiefTrap is based on a novel concept of an anti-theft honeypot account that protects the owner's data while preventing a thief from resetting the device.
We implemented the proposed scheme and evaluated it through an empirical user study with 35 participants. In this study, the owner's data could be protected, recovered, and anti-theft functionality could be performed unnoticed from the thief in all cases.
IIFA proposes a novel approach for Android's inter-component/inter-app communication (ICC/IAC) analysis. Our main contribution is the first fully automatic, sound, and precise ICC/IAC information flow analysis that is scalable for realistic apps due to modularity, avoiding combinatorial explosion: Our approach determines communicating apps using short summaries rather than inlining intent calls between components and apps, which requires simultaneously analyzing all apps installed on a device.
We evaluate IIFA in terms of precision, recall, and demonstrate its scalability to a large corpus of real-world apps. IIFA reports 62 problematic ICC-/IAC-related information flows via two or more apps/components.
PIAnalyzer proposes a novel approach to analyze PendingIntent related vulnerabilities. PendingIntents are a powerful and universal feature of Android for inter-component communication. We empirically evaluate PIAnalyzer on a set of 1000 randomly selected applications and find 1358 insecure usages of PendingIntents, including 70 severe vulnerabilities.
In this paper two new methods for the design of fault-tolerant pipelined sequential and combinational circuits, called Error Detection and Partial Error Correction (EDPEC) and Full Error Detection and Correction (FEDC), are described. The proposed methods are based on an Error Detection Logic (EDC) in the combinational circuit part combined with fault tolerant memory elements implemented using fault tolerant master–slave flip-flops. If a transient error, due to a transient fault in the combinational circuit part is detected by the EDC, the error signal controls the latching stage of the flip-flops such that the previous correct state of the register stage is retained until the transient error disappears. The system can continue to work in its previous correct state and no additional recovery procedure (with typically reduced clock frequency) is necessary. The target applications are dataflow processing blocks, for which software-based recovery methods cannot be easily applied. The presented architectures address both single events as well as timing faults of arbitrarily long duration. An example of this architecture is developed and described, based on the carry look-ahead adder. The timing conditions are carefully investigated and simulated up to the layout level. The enhancement of the baseline architecture is demonstrated with respect to the achieved fault tolerance for the single event and timing faults. It is observed that the number of uncorrected single events is reduced by the EDPEC architecture by 2.36 times compared with previous solution. The FEDC architecture further reduces the number of uncorrected events to zero and outperforms the Triple Modular Redundancy (TMR) with respect to correction of timing faults. The power overhead of both new architectures is about 26–28% lower than the TMR.
In this thesis we introduce the concept of the degree of formality. It is directed against a dualistic point of view, which only distinguishes between formal and informal proofs. This dualistic attitude does not respect the differences between the argumentations classified as informal and it is unproductive because the individual potential of the respective argumentation styles cannot be appreciated and remains untapped.
This thesis has two parts. In the first of them we analyse the concept of the degree of formality (including a discussion about the respective benefits for each degree) while in the second we demonstrate its usefulness in three case studies. In the first case study we will repair Haskell B. Curry's view of mathematics, which incidentally is of great importance in the first part of this thesis, in light of the different degrees of formality. In the second case study we delineate how awareness of the different degrees of formality can be used to help students to learn how to prove. Third, we will show how the advantages of proofs of different degrees of formality can be combined by the development of so called tactics having a medium degree of formality. Together the three case studies show that the degrees of formality provide a convincing solution to the problem of untapped potential.
Physical computing covers the design and realization of interactive objects and installations and allows learners to develop concrete, tangible products of the real world, which arise from their imagination. This can be used in computer science education to provide learners with interesting and motivating access to the different topic areas of the subject in constructionist and creative learning environments. However, if at all, physical computing has so far mostly been taught in afternoon clubs or other extracurricular settings. Thus, for the majority of students so far there are no opportunities to design and create their own interactive objects in regular school lessons.
Despite its increasing popularity also for schools, the topic has not yet been clearly and sufficiently characterized in the context of computer science education. The aim of this doctoral thesis therefore is to clarify physical computing from the perspective of computer science education and to adequately prepare the topic both content-wise and methodologically for secondary school teaching. For this purpose, teaching examples, activities, materials and guidelines for classroom use are developed, implemented and evaluated in schools.
In the theoretical part of the thesis, first the topic is examined from a technical point of view. A structured literature analysis shows that basic concepts used in physical computing can be derived from embedded systems, which are the core of a large field of different application areas and disciplines. Typical methods of physical computing in professional settings are analyzed and, from an educational perspective, elements suitable for computer science teaching in secondary schools are extracted, e. g. tinkering and prototyping. The investigation and classification of suitable tools for school teaching show that microcontrollers and mini computers, often with extensions that greatly facilitate the handling of additional components, are particularly attractive tools for secondary education. Considering the perspectives of science, teachers, students and society, in addition to general design principles, exemplary teaching approaches for school education and suitable learning materials are developed and the design, production and evaluation of a physical computing construction kit suitable for teaching is described.
In the practical part of this thesis, with “My Interactive Garden”, an exemplary approach to integrate physical computing in computer science teaching is tested and evaluated in different courses and refined based on the findings in a design-based research approach. In a series of workshops on physical computing, which is based on a concept for constructionist professional development that is developed specifically for this purpose, teachers are empowered and encouraged to develop and conduct physical computing lessons suitable for their particular classroom settings. Based on their in-class experiences, a process model of physical computing teaching is derived. Interviews with those teachers illustrate that benefits of physical computing, including the tangibility of crafted objects and creativity in the classroom, outweigh possible drawbacks like longer preparation times, technical difficulties or difficult assessment. Hurdles in the classroom are identified and possible solutions discussed.
Empirical investigations in the different settings reveal that “My Interactive Garden” and physical computing in general have a positive impact, among others, on learner motivation, fun and interest in class and perceived competencies.
Finally, the results from all evaluations are combined to evaluate the design principles for physical computing teaching and to provide a perspective on the development of decision-making aids for physical computing activities in school education.
Institutions are facing the challenge to integrate legacy systems with steadily growing new ones, using different technologies and interaction patterns. With the demand of offering the best potential of all systems, several not matching systems including their functions have to be aggregated and offered in a useable way. This paper presents an adaptive, generalizable and self-organized Personal Learning Environment (PLE) framework with the potential to integrate several heterogeneous services using a service-oriented architecture. First, a general overview over the field is given, followed by the description of the core components of the PLE framework. A prototypical implementation is presented. Finally, it’s shown how the PLE framework can be dynamically adapted to a changing system environment, reflecting experiences from first user studies.
Mobile devices and associated applications (apps) are an indispensable part of daily life and provide access to important information anytime and anywhere. However, the availability of university-wide services in the mobile sector is still poor. If they exist they usually result from individual activities of students and teachers. Mobile applications can have an essential impact on the improvement of students’ self-organization as well as on the design and enhancement of specific learning scenarios, though. This article introduces a mobile campus app framework, which integrates central campus services and decentralized learning applications. An analysis of strengths and weaknesses of different approaches is presented to summarize and evaluate them in terms of requirements, development, maintenance and operation. The article discusses the underlying service-oriented architecture that allows transferring the campus app to other universities or institutions at reasonable cost. It concludes with a presentation of the results as well as ongoing discussions and future work
In universities, diverse tools and software systems exist that each facilitates a different teaching and learning scenario. A deviating approach is taken by Personal Learning Environments (PLE) that aim to provide a common platform. Considering e-portfolios as an integral part of PLEs, especially portfolio-based learning and assessment have to be supported. Therefore, the concept of a PLE is developed further by enabling the products of different software systems to be integrated in portfolio pages and finally submitted for feedback and assessment. It is further elaborated how the PLE approach is used to support the continuous formative assessment within portfolio-based learning scenarios.
The term Personal Learning Environment (PLE) is associated with the desire to put the learner in control of his own learning process, so that he is able to set and accomplish the desired learning goals at the right time with the learning environment chosen by him. Gradually, such a learning environment includes several digital content, services and tools. It is thus summarized as the Virtual Learning Environment (VLE). Even though the construction of an individual PLE is a complex task, several approaches to support this process already exist. They mostly occur under the umbrella term PLE or with little accentuations like iPLE, which especially live within the context of institutions. This paper sums up the variety of attempts and technical approaches to establish a PLE and suggests a categorization for them.
The ongoing digitalization leads to a need of continuous change of ICT (Information and Communi-cation Technology) in all university domains and therefore affects all stakeholders in this arena. More and more ICT components, systems and tools occur and have to be integrated into the existing processes and infrastructure of the institutions. These tasks include the transfer of resources and information across multiple ICT systems. By using so-called virtual environments for domains of re-search, education, learning and work, the performance of daily tasks can be aided. Based on a user requirement analysis different short- and long-term objectives were identified and are tackled now in the context of a federal research project. In order to be prepared for the ongoing digitalization, new systems have to be provided. Both, a service-oriented infrastructure and a related web-based virtual learning environment constitute the platform Campus.UP and creates the necessary basis to be ready for future challenges. The current focus lies on e-portfolio work, hence we will present a related focus group evaluation. The results indicate a tremendous need to extend the possibilities of sharing resources across system boundaries, in order to enable a comfortable participation of exter-nal cooperating parties and to clarify the focus of each connected system. The introduction of such an infrastructure implies far-reaching changes for traditional data centers. Therefore, the challenges and risks of faculty conducting innovation projects for the ICT organization are taken as a starting point to stimulate a discussion, how data centers can utilize projects to be ready for the future needs. We are confident that Campus.UP will provide the basis for ensuring the persistent transfer of innovation to the ICT organization and thus will contribute to tackle the future challenges of digitalization.
Solving problems combining task and motion planning requires searching across a symbolic search space and a geometric search space. Because of the semantic gap between symbolic and geometric representations, symbolic sequences of actions are not guaranteed to be geometrically feasible. This compels us to search in the combined search space, in which frequent backtracks between symbolic and geometric levels make the search inefficient.We address this problem by guiding symbolic search with rich information extracted from the geometric level through culprit detection mechanisms.
Answer Set Programming (ASP) is a declarative problem solving approach, combining a rich yet simple modeling language with high-performance solving capabilities. Although this has already resulted in various applications, certain aspects of such applications are more naturally modeled using variables over finite domains, for accounting for resources, fine timings, coordinates, or functions. Our goal is thus to extend ASP with constraints over integers while preserving its declarative nature. This allows for fast prototyping and elaboration tolerant problem descriptions of resource related applications. The resulting paradigm is called Constraint Answer Set Programming (CASP).
We present three different approaches for solving CASP problems. The first one, a lazy, modular approach combines an ASP solver with an external system for handling constraints. This approach has the advantage that two state of the art technologies work hand in hand to solve the problem, each concentrating on its part of the problem. The drawback is that inter-constraint dependencies cannot be communicated back to the ASP solver, impeding its learning algorithm. The second approach translates all constraints to ASP. Using the appropriate encoding techniques, this results in a very fast, monolithic system. Unfortunately, due to the large, explicit representation of constraints and variables, translation techniques are restricted to small and mid-sized domains. The third approach merges the lazy and the translational approach, combining the strength of both while removing their weaknesses. To this end, we enhance the dedicated learning techniques of an ASP solver with the inferences of the translating approach in a lazy way. That is, the important knowledge is only made explicit when needed.
By using state of the art techniques from neighboring fields, we provide ways to tackle real world, industrial size problems. By extending CASP to reactive solving, we open up new application areas such as online planning with continuous domains and durations.
Contemporary multi-core processors are parallel systems that also provide shared memory for programs running on them. Both the increasing number of cores in so-called many-core systems and the still growing computational power of the cores demand for memory systems that are able to deliver high bandwidths. Caches are essential components to satisfy this requirement. Nevertheless, hardware-based cache coherence in many-core chips faces practical limits to provide both coherence and high memory bandwidths. In addition, a shift away from global coherence can be observed. As a result, alternative architectures and suitable programming models need to be investigated.
This thesis focuses on fast communication for non-cache-coherent many-core architectures. Experiments are conducted on the Single-Chip Cloud Computer (SCC), a non-cache-coherent many-core processor with 48 mesh-connected cores. Although originally designed for message passing, the results of this thesis show that shared memory can be efficiently used for one-sided communication on this kind of architecture. One-sided communication enables data exchanges between processes where the receiver is not required to know the details of the performed communication. In the notion of the Message Passing Interface (MPI) standard, this type of communication allows to access memory of remote processes. In order to support this communication scheme on non-cache-coherent architectures, both an efficient process synchronization and a communication scheme with software-managed cache coherence are designed and investigated.
The process synchronization realizes the concept of the general active target synchronization scheme from the MPI standard. An existing classification of implementation approaches is extended and used to identify an appropriate class for the non-cache-coherent shared memory platform. Based on this classification, existing implementations are surveyed in order to find beneficial concepts, which are then used to design a lightweight synchronization protocol for the SCC that uses shared memory and uncached memory accesses. The proposed scheme is not prone to process skew and also enables direct communication as soon as both communication partners are ready. Experimental results show very good scaling properties and up to five times lower synchronization latency compared to a tuned message-based MPI implementation for the SCC.
For the communication, SCOSCo, a shared memory approach with software-managed cache coherence, is presented. According requirements for the coherence that fulfill MPI's separate memory model are formulated, and a lightweight implementation exploiting SCC hard- and software features is developed. Despite a discovered malfunction in the SCC's memory subsystem, the experimental evaluation of the design reveals up to five times better bandwidths and nearly four times lower latencies in micro-benchmarks compared to the SCC-tuned but message-based MPI library. For application benchmarks, like a parallel 3D fast Fourier transform, the runtime share of communication can be reduced by a factor of up to five. In addition, this thesis postulates beneficial hardware concepts that would support software-managed coherence for one-sided communication on future non-cache-coherent architectures where coherence might be only available in local subdomains but not on a global processor level.
Although it has become common practice to build applications based on the reuse of existing components or services, technical complexity and semantic challenges constitute barriers to ensuring a successful and wide reuse of components and services. In the geospatial application domain, the barriers are self-evident due to heterogeneous geographic data, a lack of interoperability and complex analysis processes.
Constructing workflows manually and discovering proper services and data that match user intents and preferences is difficult and time-consuming especially for users who are not trained in software development. Furthermore, considering the multi-objective nature of environmental modeling for the assessment of climate change impacts and the various types of geospatial data (e.g., formats, scales, and georeferencing systems) increases the complexity challenges.
Automatic service composition approaches that provide semantics-based assistance in the process of workflow design have proven to be a solution to overcome these challenges and have become a frequent demand especially by end users who are not IT experts. In this light, the major contributions of this thesis are:
(i) Simplification of service reuse and workflow design of applications for climate impact analysis by following the eXtreme Model-Driven Development (XMDD) paradigm.
(ii) Design of a semantic domain model for climate impact analysis applications that comprises specifically designed services, ontologies that provide domain-specific vocabulary for referring to types and services, and the input/output annotation of the services using the terms defined in the ontologies.
(iii) Application of a constraint-driven method for the automatic composition of workflows for analyzing the impacts of sea-level rise. The application scenario demonstrates the impact of domain modeling decisions on the results and the performance of the synthesis algorithm.
Although Boolean Constraint Technology has made tremendous progress over the last decade, the efficacy of state-of-the-art solvers is known to vary considerably across different types of problem instances, and is known to depend strongly on algorithm parameters. This problem was addressed by means of a simple, yet effective approach using handmade, uniform, and unordered schedules of multiple solvers in ppfolio, which showed very impressive performance in the 2011 Satisfiability Testing (SAT) Competition. Inspired by this, we take advantage of the modeling and solving capacities of Answer Set Programming (ASP) to automatically determine more refined, that is, nonuniform and ordered solver schedules from the existing benchmarking data. We begin by formulating the determination of such schedules as multi-criteria optimization problems and provide corresponding ASP encodings. The resulting encodings are easily customizable for different settings, and the computation of optimum schedules can mostly be done in the blink of an eye, even when dealing with large runtime data sets stemming from many solvers on hundreds to thousands of instances. Also, the fact that our approach can be customized easily enabled us to swiftly adapt it to generate parallel schedules for multi-processor machines.
A multiple interpretation scheme is an ordered sequence of morphisms. The ordered multiple interpretation of a word is obtained by concatenating the images of that word in the given order of morphisms. The arbitrary multiple interpretation of a word is the semigroup generated by the images of that word. These interpretations are naturally extended to languages. Four types of ambiguity of multiple interpretation schemata on a language are defined: o-ambiguity, internal ambiguity, weakly external ambiguity and strongly external ambiguity. We investigate the problem of deciding whether a multiple interpretation scheme is ambiguous on regular languages.
Algorithm selection (AS) techniques - which involve choosing from a set of algorithms the one expected to solve a given problem instance most efficiently - have substantially improved the state of the art in solving many prominent AI problems, such as SAT, CSP, ASP, MAXSAT and QBF. Although several AS procedures have been introduced, not too surprisingly, none of them dominates all others across all AS scenarios. Furthermore, these procedures have parameters whose optimal values vary across AS scenarios. This holds specifically for the machine learning techniques that form the core of current AS procedures, and for their hyperparameters. Therefore, to successfully apply AS to new problems, algorithms and benchmark sets, two questions need to be answered: (i) how to select an AS approach and (ii) how to set its parameters effectively. We address both of these problems simultaneously by using automated algorithm configuration. Specifically, we demonstrate that we can automatically configure claspfolio 2, which implements a large variety of different AS approaches and their respective parameters in a single, highly-parameterized algorithm framework. Our approach, dubbed AutoFolio, allows researchers and practitioners across a broad range of applications to exploit the combined power of many different AS methods. We demonstrate AutoFolio can significantly improve the performance of claspfolio 2 on 8 out of the 13 scenarios from the Algorithm Selection Library, leads to new state-of-the-art algorithm selectors for 7 of these scenarios, and matches state-of-the-art performance (statistically) on all other scenarios. Compared to the best single algorithm for each AS scenario, AutoFolio achieves average speedup factors between 1.3 and 15.4.
Formalizing informal logic
(2015)
In this paper we investigate the extent to which formal argumentation models can handle ten basic characteristics of informal logic identified in the informal logic literature. By showing how almost all of these characteristics can be successfully modelled formally, we claim that good progress can be made toward the project of formalizing informal logic. Of the formal argumentation models available, we chose the Carneades Argumentation System (CAS), a formal, computational model of argument that uses argument graphs as its basis, structures of a kind very familiar to practitioners of informal logic through their use of argument diagrams.
Answer Set Programming (ASP) is an increasingly popular framework for declarative programming that admits the description of problems by means of rules and constraints that form a disjunctive logic program. In particular, many Al problems such as reasoning in a nonmonotonic setting can be directly formulated in ASP. Although the main problems of ASP are of high computational complexity, complete for the second level of the Polynomial Hierarchy, several restrictions of ASP have been identified in the literature, under which ASP problems become tractable.
In this paper we use the concept of backdoors to identify new restrictions that make ASP problems tractable. Small backdoors are sets of atoms that represent "clever reasoning shortcuts" through the search space and represent a hidden structure in the problem input. The concept of backdoors is widely used in theoretical investigations in the areas of propositional satisfiability and constraint satisfaction. We show that it can be fruitfully adapted to ASP. We demonstrate how backdoors can serve as a unifying framework that accommodates several tractable restrictions of ASP known from the literature. Furthermore, we show how backdoors allow us to deploy recent algorithmic results from parameterized complexity theory to the domain of answer set programming. (C) 2015 Elsevier B.V. All rights reserved.
Time-series data from multicomponent systems capture the dynamics of the ongoing processes and reflect the interactions between the components. The progression of processes in such systems usually involves check-points and events at which the relationships between the components are altered in response to stimuli. Detecting these events together with the implicated components can help understand the temporal aspects of complex biological systems. Here we propose a regularized regression-based approach for identifying breakpoints and corresponding segments from multivariate time-series data. In combination with techniques from clustering, the approach also allows estimating the significance of the determined breakpoints as well as the key components implicated in the emergence of the breakpoints. Comparative analysis with the existing alternatives demonstrates the power of the approach to identify biologically meaningful breakpoints in diverse time-resolved transcriptomics data sets from the yeast Saccharomyces cerevisiae and the diatom Thalassiosira pseudonana.
The Domain Name System belongs to the core services of the Internet infrastructure. Hence, DNS availability and performance is essential for the operation of the Internet and replication as well as load balancing are used for the root and top level name servers.
This paper proposes an architecture for credit based server load balancing (SLB) for DNS. Compared to traditional load balancing algorithms like round robin or least connection, the benefit of credit based SLB is that the load balancer can adapt more easily to heterogeneous load requests and back end server capacities. The challenge of this approach is the definition of a suited credit metric. While this was done before for TCP based services like HTTP, the problem was not solved for UDP based services like DNS.
In the following an approach is presented to define credits also for UDP based services. This UDP/DNS approach is implemented within the credit based SLB implementation salbnet. The presented measurements confirm the benefit of the self-adapting credit based SLB approach. In our experiments, the mean (first) response time dropped significantly compared to weighted round robin (WRR) (from over 4 ms to about 0.6 ms for dynamic pressure relieve (DPR)).
Scheduling performance in computational grid can potentially benefit a lot from accurate execution time estimation for parallel jobs. Most existing approaches for the parallel job execution time estimation, however, require ample past job traces and the explicit correlations between the job execution time and the outer layout parameters such as the consumed processor numbers, the user-estimated execution time and the job ID, which are hard to obtain or reveal. This paper presents and evaluates a novel execution time estimation approach for parallel jobs, the user-behavior clustering for execution time estimation, which can give more accurate execution time estimation for parallel jobs through exploring the job similarity and revealing the user submission patterns. Experiment results show that compared to the state-of-art algorithms, our approach can improve the accuracy of the job execution time estimation up to 5.6 %, meanwhile the time that our approach spends on calculation can be reduced up to 3.8 %.
Refined elasticity sampling for Monte Carlo-based identification of stabilizing network patterns
(2015)
Motivation: Structural kinetic modelling (SKM) is a framework to analyse whether a metabolic steady state remains stable under perturbation, without requiring detailed knowledge about individual rate equations. It provides a representation of the system's Jacobian matrix that depends solely on the network structure, steady state measurements, and the elasticities at the steady state. For a measured steady state, stability criteria can be derived by generating a large number of SKMs with randomly sampled elasticities and evaluating the resulting Jacobian matrices. The elasticity space can be analysed statistically in order to detect network positions that contribute significantly to the perturbation response. Here, we extend this approach by examining the kinetic feasibility of the elasticity combinations created during Monte Carlo sampling.
Results: Using a set of small example systems, we show that the majority of sampled SKMs would yield negative kinetic parameters if they were translated back into kinetic models. To overcome this problem, a simple criterion is formulated that mitigates such infeasible models. After evaluating the small example pathways, the methodology was used to study two steady states of the neuronal TCA cycle and the intrinsic mechanisms responsible for their stability or instability. The findings of the statistical elasticity analysis confirm that several elasticities are jointly coordinated to control stability and that the main source for potential instabilities are mutations in the enzyme alpha-ketoglutarate dehydrogenase.
Pervasive educational games have the potential to transfer learning content to real-life experiences beyond lecture rooms, through realizing field trips in an augmented or virtual manner. This article introduces the pervasive educational game "RouteMe" that brings the rather abstract topic of routing in ad hoc networks to real-world environments. The game is designed for university-level courses and supports these courses in a motivating manner to deepen the learning experience. Students slip into the role of either routing nodes or applications with routing demands. On three consecutive levels of difficulty, they get introduced with the game concept, learn the basic routing mechanisms and become aware of the general limitations and functionality of routing nodes. This paper presents the pedagogical and technical game concept as well as findings from an evaluation in a university setting.
The use of video lectures in distance learning involves the two major problems of searchability and active user participation. In this paper, we promote the implementation and usage of a collaborative educational video annotation functionality to overcome these two challenges. Different use cases and requirements, as well as details of the implementation, are explained. Furthermore, we suggest more improvements to foster a culture of participation and an algorithm for the extraction of semantic data. Finally, evaluations in the form of user tests and questionnaires in a MOOC setting are presented. The results of the evaluation are promising, as they indicate not only that students perceive it as useful, but also that the learning effectiveness increases. The combination of personal lecture video annotations with a semantic topic map was also evaluated positively and will thus be investigated further, as will the implementation in a MOOC context.
Boolean networks provide a simple yet powerful qualitative modeling approach in systems biology. However, manual identification of logic rules underlying the system being studied is in most cases out of reach. Therefore, automated inference of Boolean logical networks from experimental data is a fundamental question in this field. This paper addresses the problem consisting of learning from a prior knowledge network describing causal interactions and phosphorylation activities at a pseudo-steady state, Boolean logic models of immediate-early response in signaling transduction networks. The underlying optimization problem has been so far addressed through mathematical programming approaches and the use of dedicated genetic algorithms. In a recent work we have shown severe limitations of stochastic approaches in this domain and proposed to use Answer Set Programming (ASP), considering a simpler problem setting. Herein, we extend our previous work in order to consider more realistic biological conditions including numerical datasets, the presence of feedback-loops in the prior knowledge network and the necessity of multi-objective optimization. In order to cope with such extensions, we propose several discretization schemes and elaborate upon our previous ASP encoding. Towards real-world biological data, we evaluate the performance of our approach over in silico numerical datasets based on a real and large-scale prior knowledge network. The correctness of our encoding and discretization schemes are dealt with in Appendices A-B. (C) 2014 Elsevier B.V. All rights reserved.
In task-oriented communication, references often need to be effective in their distinctive function, that is, help the hearer identify the referent correctly and as effortlessly as possible. However, it can be challenging for computational or empirical studies to capture referential effectiveness. Empirical findings indicate that human-produced references are not always optimally effective, and that their effectiveness may depend on different aspects of the situational context that can evolve dynamically over the course of an interaction. On this basis, we propose a computational model of effective reference generation which distinguishes speaker behaviour according to its helpfulness to the hearer in a certain situation, and explicitly aims at modelling highly helpful speaker behaviour rather than speaker behaviour invariably. Our model, which extends the planning-based paradigm of sentence generation with a statistical account of effectiveness, can adapt to the situational context by making this distinction newly for each new reference. We find that the generated references resemble those of effective human speakers more closely than references of baseline models, and that they are resolved correctly more often than those of other models participating in a shared-task evaluation with human hearers. Finally, we argue that the model could serve as a methodological framework for computational and empirical research on referential effectiveness.
The UDKM1DSIM toolbox is a collection of MATLAB (MathWorks Inc.) classes and routines to simulate the structural dynamics and the according X-ray diffraction response in one-dimensional crystalline sample structures upon an arbitrary time-dependent external stimulus, e.g. an ultrashort laser pulse. The toolbox provides the capabilities to define arbitrary layered structures on the atomic level including a rich database of corresponding element-specific physical properties. The excitation of ultrafast dynamics is represented by an N-temperature model which is commonly applied for ultrafast optical excitations. Structural dynamics due to thermal stress are calculated by a linear-chain model of masses and springs. The resulting X-ray diffraction response is computed by dynamical X-ray theory. The UDKM1DSIM toolbox is highly modular and allows for introducing user-defined results at any step in the simulation procedure.
Program summary
Program title: udkm1Dsim
Catalogue identifier: AERH_v1_0
Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AERH_v1_0.html
Licensing provisions: BSD
No. of lines in distributed program, including test data, etc.: 130221
No. of bytes in distributed program, including test data, etc.: 2746036
Distribution format: tar.gz
Programming language: Matlab (MathWorks Inc.).
Computer: PC/Workstation.
Operating system: Running Matlab installation required (tested on MS Win XP -7, Ubuntu Linux 11.04-13.04).
Has the code been vectorized or parallelized?: Parallelization for dynamical XRD computations. Number of processors used: 1-12 for Matlab Parallel Computing Toolbox; 1 - infinity for Matlab Distributed Computing Toolbox
External routines:
Optional: Matlab Parallel Computing Toolbox, Matlab Distributed Computing Toolbox Required (included in the package): mtimesx Fast Matrix Multiply for Matlab by James Tursa, xml io tools by Jaroslaw Tuszynski, textprogressbar by Paul Proteus
Nature of problem:
Simulate the lattice dynamics of 1D crystalline sample structures due to an ultrafast excitation including thermal transport and compute the corresponding transient X-ray diffraction pattern.
Solution method:
Restrictions:
The program is restricted to 1D sample structures and is further limited to longitudinal acoustic phonon modes and symmetrical X-ray diffraction geometries.
Unusual features: The program is highly modular and allows the inclusion of user-defined inputs at any time of the simulation procedure.
Running time: The running time is highly dependent on the number of unit cells in the sample structure and other simulation parameters such as time span or angular grid for X-ray diffraction computations. However, the example files are computed in approx. 1-5 min each on a 8 Core Processor with 16 GB RAM available.
The correctness of model transformations is a crucial element for model-driven engineering of high-quality software. A prerequisite to verify model transformations at the level of the model transformation specification is that an unambiguous formal semantics exists and that the implementation of the model transformation language adheres to this semantics. However, for existing relational model transformation approaches, it is usually not really clear under which constraints particular implementations really conform to the formal semantics. In this paper, we will bridge this gap for the formal semantics of triple graph grammars (TGG) and an existing efficient implementation. While the formal semantics assumes backtracking and ignores non-determinism, practical implementations do not support backtracking, require rule sets that ensure determinism, and include further optimizations. Therefore, we capture how the considered TGG implementation realizes the transformation by means of operational rules, define required criteria, and show conformance to the formal semantics if these criteria are fulfilled. We further outline how static and runtime checks can be employed to guarantee these criteria.
In object-oriented programming, polymorphic dispatch of operations decouples clients from specific providers of services and allows implementations to be modified or substituted without affecting clients.
The Uniform Access Principle (UAP) tries to extend these qualities to resource access by demanding that access to state be indistinguishable from access to operations. Despite language features supporting the UAP, the overall goal of substitutability has not been achieved for either alternative resources such as keyed storage, files or web pages, or for alternate access mechanisms: specific kinds of resources are bound to specific access mechanisms and vice versa. Changing storage or access patterns either requires changes to both clients and service providers and trying to maintain the UAP imposes significant penalties in terms of code-duplication and/or performance overhead.
We propose introducing first class identifiers as polymorphic names for storage locations to solve these problems. With these Polymorphic Identifiers, we show that we can provide uniform access to a wide variety of resource types as well as storage and access mechanisms, whether parametrized or direct, without affecting client code, without causing code duplication or significant performance penalties.
In this article, we present our experience with over a decade of strict simplicity orientation in the development and evolution of plug-ins. The point of our approach is to enable our graphical modeling framework jABC to capture plug-in development in a domain-specific setting. The typically quite tedious and technical plug-in development is shifted this way from a programming task to the modeling level, where it can be mastered also by application experts without programming expertise. We show how the classical plug-in development profits from a systematic domain-specific API design and how the level of abstraction achieved this way can be further enhanced by defining adequate building blocks for high-level plug-in modeling. As the resulting plug-in models can be compiled and deployed automatically, our approach decomposes plug-in development into three phases where only the realization phase requires plug-in-specific effort. By using our modeling framework jABC, this effort boils down to graphical, tool-supported process modeling. Furthermore, we support the automatic completion of process sketches for executability. All this will be illustrated along the most recent plug-in-based evolution of the jABC framework, which witnessed quite some bootstrapping effects.
The submission and management of computational jobs is a traditional part of utility computing environments. End users and developers of domain-specific software abstractions often have to deal with the heterogeneity of such batch processing systems. This lead to a number of application programming interface and job description standards in the past, which are implemented and established for cluster and Grid systems. With the recent rise of cloud computing as new utility computing paradigm, the standardized access to batch processing facilities operated on cloud resources becomes an important issue. Furthermore, the design of such a standard has to consider a tradeoff between feature completeness and the achievable level of interoperability. The article discusses this general challenge, and presents some existing standards with traditional cluster and Grid computing background that may be applicable to cloud environments. We present OCCI-DRMAA as one approach for standardized access to batch processing facilities hosted in a cloud.
claspfolio 2
(2014)
Building on the award-winning, portfolio-based ASP solver claspfolio, we present claspfolio 2, a modular and open solver architecture that integrates several different portfolio-based algorithm selection approaches and techniques. The claspfolio 2 solver framework supports various feature generators, solver selection approaches, solver portfolios, as well as solver-schedule-based pre-solving techniques. The default configuration of claspfolio 2 relies on a light-weight version of the ASP solver clasp to generate static and dynamic instance features. The flexible open design of claspfolio 2 is a distinguishing factor even beyond ASP. As such, it provides a unique framework for comparing and combining existing portfolio-based algorithm selection approaches and techniques in a single, unified framework. Taking advantage of this, we conducted an extensive experimental study to assess the impact of different feature sets, selection approaches and base solver portfolios. In addition to gaining substantial insights into the utility of the various approaches and techniques, we identified a default configuration of claspfolio 2 that achieves substantial performance gains not only over clasp's default configuration and the earlier version of claspfolio, but also over manually tuned configurations of clasp.
Students beginning their studies at university face manifold problems such as orientation in a new environment and organizing their courses. This article presents the implementation and successful empirical evaluation of the pervasive browser-based educational game "FreshUP", which aims at helping to overcome the initial difficulties of freshmen. In contrast to a conventional scavenger hunt, mobile pervasive games like FreshUP, bridging in-game and real world activities, have the potential to provide help in a motivating manner using new technology which is currently becoming more and more common. (C) 2013 Elsevier B.V. All rights reserved.
Researchers and developers worldwide have put their efforts into the design, development and use of information and communication technology to support teaching and learning. This research is driven by pedagogical as well as technological disciplines. The most challenging ideas are currently found in the application of mobile, ubiquitous, pervasive, contextualized and seamless technologies for education, which we shall refer to as pervasive education. This article provides a comprehensive overview of the existing work in this field and categorizes it with respect to educational settings. Using this approach, best practice solutions for certain educational settings and open questions for pervasive education are highlighted in order to inspire interested developers and educators. The work is assigned to different fields, identified by the main pervasive technologies used and the educational settings. Based on these assignments we identify areas within pervasive education that are currently disregarded or deemed challenging so that further research and development in these fields are stimulated in a trans-disciplinary approach. (C) 2013 Elsevier B.V. All rights reserved.
While the maturity of process mining algorithms increases and more process mining tools enter the market, process mining projects still face the problem of different levels of abstraction when comparing events with modeled business activities. Current approaches for event log abstraction try to abstract from the events in an automated way that does not capture the required domain knowledge to fit business activities. This can lead to misinterpretation of discovered process models. We developed an approach that aims to abstract an event log to the same abstraction level that is needed by the business. We use domain knowledge extracted from existing process documentation to semi-automatically match events and activities. Our abstraction approach is able to deal with n:m relations between events and activities and also supports concurrency. We evaluated our approach in two case studies with a German IT outsourcing company. (C) 2014 Elsevier Ltd. All rights reserved.
Recent evidence suggests that metabolic changes play a pivotal role in the biology of cancer and in particular renal cell carcinoma (RCC). Here, a global metabolite profiling approach was applied to characterize the metabolite pool of RCC and normal renal tissue. Advanced decision tree models were applied to characterize the metabolic signature of RCC and to explore features of metastasized tumours. The findings were validated in a second independent dataset. Vitamin E derivates and metabolites of glucose, fatty acid, and inositol phosphate metabolism determined the metabolic profile of RCC. alpha-tocopherol, hippuric acid, myoinositol, fructose-1-phosphate and glucose-1-phosphate contributed most to the tumour/normal discrimination and all showed pronounced concentration changes in RCC. The identified metabolic profile was characterized by a low recognition error of only 5% for tumour versus normal samples. Data on metastasized tumours suggested a key role for metabolic pathways involving arachidonic acid, free fatty acids, proline, uracil and the tricarboxylic acid cycle. These results illustrate the potential of mass spectroscopy based metabolomics in conjunction with sophisticated data analysis methods to uncover the metabolic phenotype of cancer. Differentially regulated metabolites, such as vitamin E compounds, hippuric acid and myoinositol, provide leads for the characterization of novel pathways in RCC.
We introduce hierarchical kFOIL as a simple extension of the multitask kFOIL learning algorithm. The algorithm first learns a core logic representation common to all tasks, and then refines it by specialization on a per-task basis. The approach can be easily generalized to a deeper hierarchy of tasks. A task clustering algorithm is also proposed in order to automatically generate the task hierarchy. The approach is validated on problems of drug-resistance mutation prediction and protein structural classification. Experimental results show the advantage of the hierarchical version over both single and multi task alternatives and its potential usefulness in providing explanatory features for the domain. Task clustering allows to further improve performance when a deeper hierarchy is considered.
We address the problem of Finite Model Computation (FMC) of first-order theories and show that FMC can efficiently and transparently be solved by taking advantage of a recent extension of Answer Set Programming (ASP), called incremental Answer Set Programming (iASP). The idea is to use the incremental parameter in iASP programs to account for the domain size of a model. The FMC problem is then successively addressed for increasing domain sizes until an answer set, representing a finite model of the original first-order theory, is found. We implemented a system based on the iASP solver iClingo and demonstrate its competitiveness by showing that it slightly outperforms the winner of the FNT division of CADE's 2009 Automated Theorem Proving (ATP) competition on the respective benchmark collection.
Autonomy is an emerging paradigm for the design and implementation of managed services and systems. Self-managed aspects frequently concern the communication of systems with their environment. Self-management subsystems are critical, they should thus be designed and implemented as high-assurance components. Here, we propose to use GEAR, a game-based model checker for the full modal mu-calculus, and derived, more user-oriented logics, as a user friendly tool that can offer automatic proofs of critical properties of such systems. Designers and engineers can interactively investigate automatically generated winning strategies resulting from the games, this way exploring the connection between the property, the system, and the proof. The benefits of the approach are illustrated on a case study that concerns the ExoMars Rover.
We define and study quantum cellular automata (QCA). We show that they are reversible and that the neighborhood of the inverse is the opposite of the neighborhood. We also show that QCA always admit, modulo shifts, a two-layered block representation. Note that the same two-layered block representation result applies also over infinite configurations, as was previously shown for one-dimensional systems in the more elaborate formalism of operators algebras [18]. Here the proof is simpler and self-contained, moreover we discuss a counterexample QCA in higher dimensions.
One of the goals of artificial intelligence is to develop agents that learn and act in complex environments. Realistic environments typically feature a variable number of objects, relations amongst them, and non-deterministic transition behavior. While standard probabilistic sequence models provide efficient inference and learning techniques for sequential data, they typically cannot fully capture the relational complexity. On the other hand, statistical relational learning techniques are often too inefficient to cope with complex sequential data. In this paper, we introduce a simple model that occupies an intermediate position in this expressiveness/efficiency trade-off. It is based on CP-logic (Causal Probabilistic Logic), an expressive probabilistic logic for modeling causality. However, by specializing CP-logic to represent a probability distribution over sequences of relational state descriptions and employing a Markov assumption, inference and learning become more tractable and effective. Specifically, we show how to solve part of the inference and learning problems directly at the first-order level, while transforming the remaining part into the problem of computing all satisfying assignments for a Boolean formula in a binary decision diagram. We experimentally validate that the resulting technique is able to handle probabilistic relational domains with a substantial number of objects and relations.
In this paper we consider masking of unknowns (X-values) for VLSI circuits. We present a new hierarchical method of X-masking which is a major improvement of the method proposed in [4], called WIDE1. By the method proposed, the number of observable scan cells is optimized and data volume for X-masking can be significantly reduced in comparison to WIDEL This is demonstrated for three industrial designs. In cases where all X-values have to be masked the novel approach is especially efficient.
We investigate the decidability of the operation problem for TOL languages and subclasses. Fix an operation on formal languages. Given languages from the family considered (OL languages, TOL languages, or their propagating variants), is the application of this operation to the given languages still a language that belongs to the same language family? Observe, that all the Lindenmayer language families in question are anti-AFLs, that is, they are not closed under homomorphisms, inverse homomorphisms, intersection with regular languages, union, concatenation, and Kleene closure. Besides these classical operations we also consider intersection and substitution, since the language families under consideration are not closed under these operations, too. We show that for all of the above mentioned language operations, except for the Kleene closure, the corresponding operation problems of OL and TOL languages and their propagating variants are not even semidecidable. The situation changes for unary OL languages. In this case we prove that the operation problems with respect to Kleene star, complementation, and intersection with regular sets are decidable.
We introduce an approach to detecting inconsistencies in large biological networks by using answer set programming. To this end, we build upon a recently proposed notion of consistency between biochemical/genetic reactions and high-throughput profiles of cell activity. We then present an approach based on answer set programming to check the consistency of large-scale data sets. Moreover, we extend this methodology to provide explanations for inconsistencies by determining minimal representations of conflicts. In practice, this can be used to identify unreliable data or to indicate missing reactions.
Engineering of process-driven business applications can be supported by process modeling efforts in order to bridge the gap between business requirements and system specifications. However, diverging purposes of business process modeling initiatives have led to significant problems in aligning related models at different abstract levels and different perspectives. Checking the consistency of such corresponding models is a major challenge for process modeling theory and practice. In this paper, we take the inappropriateness of existing strict notions of behavioral equivalence as a starting point. Our contribution is a concept called behavioral profile that captures the essential behavioral constraints of a process model. We show that these profiles can be computed efficiently, i.e., in cubic time for sound free-choice Petri nets w.r.t. their number of places and transitions. We use behavioral profiles for the definition of a formal notion of consistency which is less sensitive to model projections than common criteria of behavioral equivalence and allows for quantifying deviation in a metric way. The derivation of behavioral profiles and the calculation of a degree of consistency have been implemented to demonstrate the applicability of our approach. We also report the findings from checking consistency between partially overlapping models of the SAP reference model.
Secondary activation of the endothelin system is thought to be involved in toxic liver injury. This study tested the hypothesis that dual endothelin-converting enzyme / neutral endopeptidase blockade might: be able to attenuate acute toxic liver injury.
Male Sprague-Dawley rats were implanted with subcutaneous minipumps to deliver the novel compound SLV338 (10 mg/kg*d) or vehicle. Four days later they received two intraperitoneal injections of D-galactosamine (1.3 g/kg each) or vehicle at an interval of 12 hours. The animals were sacrificed 48 hours after the first injection.
Injection of D-galactosamine resulted in very severe liver injury, reflected by strongly elevated plasma liver enzymes, hepatic necrosis and inflammation, and a mortality rate of 42.9 %. SLV338 treatment did not show any significant effect on the extent of acute liver injury as judged from plasma parameters, hepatic histology and mortality. Plasma measurements of SLV338 confirmed adequate drug delivery. Plasma concentrations of big endothelin-1 and endothelin-1 were significantly elevated in animals with liver injury (5-fold and 62-fold, respectively). Plasma endothelin-1 was significantly correlated with several markers of liver injury. SLV338 completely prevented the rise of plasma big endothelin-1 (p<0.05) and markedly attenuated the rise of endothelin-1 (p = 0.055).
In conclusion, dual endothelin-converting enzyme / neutral endopeptidase blockade by SLV338 did not significantly attenuate D-galactosamine-induced acute liver injury, although it largely prevented the activation of the endothelin system. An evaluation of SLV338 in a less severe model of liver injury would be of interest, since very severe intoxication might not be relevantly amenable to pharmacological interventions.
Preference handling and optimization are indispensable means for addressing nontrivial applications in Answer Set Programming (ASP). However, their implementation becomes difficult whenever they bring about a significant increase in computational complexity. As a consequence, existing ASP systems do not offer complex optimization capacities, supporting, for instance, inclusion-based minimization or Pareto efficiency. Rather, such complex criteria are typically addressed by resorting to dedicated modeling techniques, like saturation. Unlike the ease of common ASP modeling, however, these techniques are rather involved and hardly usable by ASP laymen. We address this problem by developing a general implementation technique by means of meta-prpogramming, thus reusing existing ASP systems to capture various forms of qualitative preferences among answer sets. In this way, complex preferences and optimization capacities become readily available for ASP applications.
Building biological models by inferring functional dependencies from experimental data is an important issue in Molecular Biology. To relieve the biologist from this traditionally manual process, various approaches have been proposed to increase the degree of automation. However, available approaches often yield a single model only, rely on specific assumptions, and/or use dedicated, heuristic algorithms that are intolerant to changing circumstances or requirements in the view of the rapid progress made in Biotechnology. Our aim is to provide a declarative solution to the problem by appeal to Answer Set Programming (ASP) overcoming these difficulties. We build upon an existing approach to Automatic Network Reconstruction proposed by part of the authors. This approach has firm mathematical foundations and is well suited for ASP due to its combinatorial flavor providing a characterization of all models explaining a set of experiments. The usage of ASP has several benefits over the existing heuristic algorithms. First, it is declarative and thus transparent for biological experts. Second, it is elaboration tolerant and thus allows for an easy exploration and incorporation of biological constraints. Third, it allows for exploring the entire space of possible models. Finally, our approach offers an excellent performance, matching existing, special-purpose systems.
Behavioral models capture operational principles of real-world or designed systems. Formally, each behavioral model defines the state space of a system, i.e., its states and the principles of state transitions. Such a model is the basis for analysis of the system's properties. In practice, state spaces of systems are immense, which results in huge computational complexity for their analysis. Behavioral models are typically described as executable graphs, whose execution semantics encodes a state space. The structure theory of behavioral models studies the relations between the structure of a model and the properties of its state space. In this article, we use the connectivity property of graphs to achieve an efficient and extensive discovery of the compositional structure of behavioral models; behavioral models get stepwise decomposed into components with clear structural characteristics and inter-component relations. At each decomposition step, the discovered compositional structure of a model is used for reasoning on properties of the whole state space of the system. The approach is exemplified by means of a concrete behavioral model and verification criterion. That is, we analyze workflow nets, a well-established tool for modeling behavior of distributed systems, with respect to the soundness property, a basic correctness property of workflow nets. Stepwise verification allows the detection of violations of the soundness property by inspecting small portions of a model, thereby considerably reducing the amount of work to be done to perform soundness checks. Besides formal results, we also report on findings from applying our approach to an industry model collection.
Indoor position estimation constitutes a central task in home-based assisted living environments. Such environments often rely on a heterogeneous collection of low-cost sensors whose diversity and lack of precision has to be compensated by advanced techniques for localization and tracking. Although there are well established quantitative methods in robotics and neighboring fields for addressing these problems, they lack advanced knowledge representation and reasoning capacities. Such capabilities are not only useful in dealing with heterogeneous and incomplete information but moreover they allow for a better inclusion of semantic information and more general homecare and patient-related knowledge. We address this problem and investigate how state-of-the-art localization and tracking methods can be combined with Answer Set Programming, as a popular knowledge representation and reasoning formalism. We report upon a case-study and provide a first experimental evaluation of knowledge-based position estimation both in a simulated as well as in a real setting.
Automatic code generation is an essential cornerstone of today's model-driven approaches to software engineering. Thus a key requirement for the success of this technique is the reliability and correctness of code generators. This article describes how we employ standard model checking-based verification to check that code generator models developed within our code generation framework Genesys conform to (temporal) properties. Genesys is a graphical framework for the high-level construction of code generators on the basis of an extensible library of well-defined building blocks along the lines of the Extreme Model-Driven Development paradigm. We will illustrate our verification approach by examining complex constraints for code generators, which even span entire model hierarchies. We also show how this leads to a knowledge base of rules for code generators, which we constantly extend by e.g. combining constraints to bigger constraints, or by deriving common patterns from structurally similar constraints. In our experience, the development of code generators with Genesys boils down to re-instantiating patterns or slightly modifying the graphical process model, activities which are strongly supported by verification facilities presented in this article.
Untitled
(2011)
Using the notion of an elementary loop, Gebser and Schaub (2005. Proceedings of the Eighth International Conference on Logic Programming and Nonmonotonic Reasoning (LPNMR'05), 53-65) refined the theorem on loop formulas attributable to Lin and Zhao (2004) by considering loop formulas of elementary loops only. In this paper, we reformulate the definition of an elementary loop, extend it to disjunctive programs, and study several properties of elementary loops, including how maximal elementary loops are related to minimal unfounded sets. The results provide useful insights into the stable model semantics in terms of elementary loops. For a nondisjunctive program, using a graph-theoretic characterization of an elementary loop, we show that the problem of recognizing an elementary loop is tractable. On the other hand, we also show that the corresponding problem is coNP-complete for a disjunctive program. Based on the notion of an elementary loop, we present the class of Head-Elementary-loop-Free (HEF) programs, which strictly generalizes the class of Head-Cycle-Free (HCF) programs attributable to Ben-Eliyahu and Dechter (1994. Annals of Mathematics and Artificial Intelligence 12, 53-87). Like an Ha: program, an HEF program can be turned into an equivalent nondisjunctive program in polynomial time by shifting head atoms into the body.
Parallel communicating finite automata (PCFAs) are systems of several finite state automata which process a common input string in a parallel way and are able to communicate by sending their states upon request. We consider deterministic and nondeterministic variants and distinguish four working modes. It is known that these systems in the most general mode are as powerful as one-way multi-head finite automata. It is additionally known that the number of heads corresponds to the number of automata in PCFAs in a constructive way. Thus, undecidability results as well as results on the hierarchies induced by the number of heads carry over from multi-head finite automata to PCFAs in the most general mode. Here, we complement these undecidability and hierarchy results also for the remaining working modes. In particular, we show that classical decidability questions are not semi-decidable for any type of PCFAs under consideration. Moreover, it is proven that the number of automata in the system induces infinite hierarchies for deterministic and nondeterministic PCFAs in three working modes.
Hybrid terrains are a convenient approach for the representation of digital terrain models, integrating heterogeneous data from different sources. In this article, we present a general, efficient scheme for achieving interactive level-of-detail rendering of hybrid terrain models, without the need for a costly preprocessing or resampling of the original data. The presented method works with hybrid digital terrains combining regular grid data and local high-resolution triangulated irregular networks. Since grid and triangulated irregular network data may belong to different datasets, a straightforward combination of both geometries would lead to meshes with holes and overlapping triangles. Our method generates a single multiresolution model integrating the different parts in a coherent way, by performing an adaptive tessellation of the region between their boundaries. Hence, our solution is one of the few existing approaches for integrating different multiresolution algorithms within the same terrain model, achieving a simple interactive rendering of complex hybrid terrains.
Systems of parallel finite automata communicating by states are investigated. We consider deterministic and nondeterministic devices and distinguish four working modes. It is known that systems in the most general mode are as powerful as one-way multi-head finite automata. Here we solve some open problems on the computational capacity of systems working in the remaining modes. In particular, it is shown that deterministic returning and non-returning devices are equivalent, and that there are languages which are accepted by deterministic returning and centralized systems but cannot be accepted by deterministic non-returning centralized systems. Furthermore, we show that nondeterministic systems are strictly more powerful than their deterministic variants in all the four working modes. Finally, incomparability with the classes of (deterministic) (linear) context-free languages as well as the Church-Rosser languages is derived.
This paper presents a highly effective compactor architecture for processing test responses with a high percentage of x-values. The key component is a hierarchical configurable masking register, which allows the compactor to dynamically adapt to and provide excellent performance over a wide range of x-densities. A major contribution of this paper is a technique that enables the efficient loading of the x-masking data into the masking logic in a parallel fashion using the scan chains. A method for eliminating the requirement for dedicated mask control signals using automated test equipment timing flexibility is also presented. The proposed compactor is especially suited to multisite testing. Experiments with industrial designs show that the proposed compactor enables compaction ratios exceeding 200x.
We construct a new RC phase shift network based Chua's circuit, which exhibits a period-doubling bifurcation route to chaos. Using coupled versions of such a phase-shift network based Chua's oscillators, we describe a new method for achieving complete synchronization (CS), approximate lag synchronization (LS), and approximate anticipating synchronization (AS) without delay or parameter mismatch. Employing the Pecora and Carroll approach, chaos synchronization is achieved in coupled chaotic oscillators, where the drive system variables control the response system. As a result, AS or LS or CS is demonstrated without using a variable delay line both experimentally and numerically.
We present the new multi-threaded version of the state-of-the-art answer set solver clasp. We detail its component and communication architecture and illustrate how they support the principal functionalities of clasp. Also, we provide some insights into the data representation used for different constraint types handled by clasp. All this is accompanied by an extensive experimental analysis of the major features related to multi-threading in clasp.
We present the hybrid ASP solver clingcon, combining the simple modeling language and the high performance Boolean solving capacities of Answer Set Programming (ASP) with techniques for using non-Boolean constraints from the area of Constraint Programming (CP). The new clingcon system features an extended syntax supporting global constraints and optimize statements for constraint variables. The major technical innovation improves the interaction between ASP and CP solver through elaborated learning techniques based on irreducible inconsistent sets. A broad empirical evaluation shows that these techniques yield a performance improvement of an order of magnitude.
We introduce an approach to computing answer sets of logic programs, based on concepts successfully applied in Satisfiability (SAT) checking. The idea is to view inferences in Answer Set Programming (ASP) as unit propagation on nogoods. This provides us with a uniform constraint-based framework capturing diverse inferences encountered in ASP solving. Moreover, our approach allows us to apply advanced solving techniques from the area of SAT. As a result, we present the first full-fledged algorithmic framework for native conflict-driven ASP solving. Our approach is implemented in the ASP solver clasp that has demonstrated its competitiveness and versatility by winning first places at various solver contests.
The standard assumption of identically distributed training and test data is violated when the test data are generated in response to the presence of a predictive model. This becomes apparent, for example, in the context of email spam filtering. Here, email service providers employ spam filters, and spam senders engineer campaign templates to achieve a high rate of successful deliveries despite the filters. We model the interaction between the learner and the data generator as a static game in which the cost functions of the learner and the data generator are not necessarily antagonistic. We identify conditions under which this prediction game has a unique Nash equilibrium and derive algorithms that find the equilibrial prediction model. We derive two instances, the Nash logistic regression and the Nash support vector machine, and empirically explore their properties in a case study on email spam filtering.
Information integration across company borders becomes increasingly important for the success of product lifecycle management in industry and complex supply chains. Semantic technologies are about to play a crucial role in this integrative process. However, cross-company data exchange requires mechanisms to enable fine-grained access control definition and enforcement, preventing unauthorized leakage of confidential data across company borders. Currently available semantic repositories are not sufficiently equipped to satisfy this important requirement. This paper presents an infrastructure for controlled sharing of semantic data between cooperating business partners. First, we motivate the need for access control in semantic data federations by a case study in the industrial service sector. Furthermore, we present an architecture for controlling access to semantic repositories that is based on our newly developed SemForce security service. Finally, we show the practical feasibility of this architecture by an implementation and several performance experiments.
Programmers make many changes to the program to eventually find a good solution for a given task. In this course of change, every intermediate development state can of value, when, for example, a promising ideas suddenly turn out inappropriate or the interplay of objects turns out more complex than initially expected before making changes. Programmers would benefit from tool support that provides immediate access to source code and run-time of previous development states of interest. We present IDE extensions, implemented for Squeak/Smalltalk, to preserve, retrieve, and work with this information. With such tool support, programmers can work without worries because they can rely on tools that help them with whatever their explorations will reveal. They no longer have to follow certain best practices only to avoid undesired consequences of changing code.
This paper presents an evaluation of ACPI energy saving modes, and deduces the design and implementation of an energy saving daemon for clusters called cherub. The design of the cherub daemon is modular and extensible. Since the only requirement is a central approach for resource management, cherub is suited for Server Load Balancing (SLB) clusters managed by dispatchers like Linux Virtual Server (LVS), as well as for High Performance Computing (HPC) clusters. Our experimental results show that cherub's scheduling algorithm works well, i.e. it will save energy, if possible, and avoids state-flapping.