Institut für Informatik und Computational Science
Refine
Year of publication
- 2023 (1)
- 2022 (12)
- 2021 (13)
- 2020 (22)
- 2019 (10)
- 2018 (21)
- 2017 (4)
- 2016 (9)
- 2015 (63)
- 2014 (29)
- 2013 (37)
- 2012 (23)
- 2011 (27)
- 2010 (32)
- 2009 (26)
- 2008 (1)
- 2007 (24)
- 2006 (38)
- 2005 (29)
- 2004 (27)
- 2003 (18)
- 2002 (15)
- 2001 (20)
- 2000 (31)
- 1999 (29)
- 1998 (30)
- 1997 (22)
- 1996 (25)
- 1995 (15)
- 1994 (17)
- 1993 (1)
Document Type
- Article (672) (remove)
Keywords
- Didaktik (13)
- Ausbildung (12)
- Hochschuldidaktik (12)
- Informatik (12)
- Answer set programming (10)
- answer set programming (8)
- Answer Set Programming (6)
- Computer Science Education (4)
- E-Learning (4)
- Competence Measurement (3)
- Machine learning (3)
- Secondary Education (3)
- Theory (3)
- formal languages (3)
- monitoring (3)
- Analytical models (2)
- Automata systems (2)
- Big Data (2)
- Competence Modelling (2)
- Computational thinking (2)
- Digitale Medien (2)
- E-learning (2)
- Equilibrium logic (2)
- Event mapping (2)
- Fault tolerance (2)
- IT-Infrastruktur (2)
- Informatics Education (2)
- Informatics Modelling (2)
- Informatics System Application (2)
- Informatics System Comprehension (2)
- Lindenmayer systems (2)
- Non-monotonic reasoning (2)
- Parameterized complexity (2)
- Process mining (2)
- ResNet (2)
- Strategie (2)
- bioinformatics (2)
- computational thinking (2)
- computer science education (2)
- cooperating systems (2)
- e-learning (2)
- education (2)
- higher education (2)
- online learning (2)
- radhard design (2)
- relevance (2)
- security (2)
- tools (2)
- (FPGA) (1)
- 2-tag system (1)
- 21st century skills, (1)
- 3D modeling (1)
- 3D visualization (1)
- ABRACADABRA (1)
- AODV (1)
- ARCS Modell (1)
- ASIC (1)
- Abstraction (1)
- Access control (1)
- Achievement (1)
- Active evaluation (1)
- Activity Theory (1)
- Activity-orientated Learning (1)
- Ad hoc routing (1)
- Adaptivity (1)
- Adaptivität (1)
- Advanced Video Codec (AVC) (1)
- Aggregates (1)
- Algorithm configuration (1)
- Algorithm portfolios (1)
- Android hybrid apps (1)
- Animal building (1)
- Anti-cancer drugs (1)
- Arduino (1)
- Argumentation structure (1)
- Assessment (1)
- Audience Response Systeme (1)
- Augmentation (1)
- Augmented and virtual reality (1)
- Austria (1)
- Autismus (1)
- Automated Theorem Proving (1)
- Automated parallelization (1)
- Automatic Item Generation (1)
- Automatically controlled windows (1)
- Automatisches Beweisen (1)
- Backdoors (1)
- Batch processing (1)
- Benchmark testing; (1)
- Berliner Modell (1)
- Blended Learning (1)
- Blind users (1)
- Bloom’s Taxonomy (1)
- Boolean logic models (1)
- Business process intelligence (1)
- CP-Logic (1)
- CS concepts (1)
- Campus (1)
- Capability approach (1)
- Challenges (1)
- Circuit faults (1)
- Clause Learning (1)
- Clock tree (1)
- Cloud (1)
- Cluster Computing (1)
- Cluster computing (1)
- Code generation (1)
- Cognitive Skills (1)
- Coherent phonons (1)
- Combinatorial multi-objective optimization (1)
- Competences (1)
- Competencies (1)
- Complex optimization (1)
- Complexity (1)
- Computational Thinking (1)
- Computational complexity (1)
- Computational grid (1)
- Computer Science (1)
- Computer Science in Context (1)
- Computer security (1)
- Computergestützes Training (1)
- Computing (1)
- Computing with DNA (1)
- Conformant Planning (1)
- Conrad Hal Waddington (1)
- Constraint satisfaction (1)
- Contest (1)
- Context awareness (1)
- Contextualisation (1)
- Contextualized learning (1)
- Continuous Testing (1)
- Continuous Versioning (1)
- Contradictions (1)
- Convolution (1)
- Course timetabling (1)
- Curriculum (1)
- Curriculum Development (1)
- Customer ownership (1)
- D-galactosamine (1)
- DMR (1)
- DNA hairpin formation (1)
- DPLL (1)
- DRMAA (1)
- DRMS (1)
- Data Analysis (1)
- Data Management (1)
- Data Privacy (1)
- Data federation (1)
- Database (1)
- Databases (1)
- Deal of the Day (1)
- Debugging (1)
- Decidability (1)
- Declare (1)
- Deep learning (1)
- Defining characteristics of physical computing (1)
- Denotational semantics (1)
- Design (1)
- Design for testability (DFT) (1)
- Digital Competence (1)
- Digital Education (1)
- Digital Game Based Learning (1)
- Digital Revolution (1)
- Digitalisierung (1)
- Digitalization (1)
- Double cell upsets (DCUs) (1)
- Dynamic assessment (1)
- Dynamical X-ray theory (1)
- E-Assessment (1)
- E-Klausuren (1)
- E-Portfolio (1)
- E-teaching (1)
- EDC (1)
- EEG (1)
- Early Literacy (1)
- Educational Standards (1)
- Educational game (1)
- Educational software (1)
- Educational timetabling (1)
- Elektronisches Prüfen (1)
- Embedded Systems (1)
- Encoding (1)
- Engines (1)
- Entity Linking (1)
- Epigenetic landscape (1)
- Epistemic Logic Programs (1)
- Euclid’s algorithm (1)
- Evaluation (1)
- Evolution (1)
- Experimentation (1)
- Explicit negation (1)
- Explore-first Programming (1)
- Extensibility (1)
- Extreme Model-Driven Development (1)
- FEDC (1)
- FPGA (1)
- Facebook (1)
- Fault Localization (1)
- Fault tolerant systems (1)
- Feature extraction (1)
- Fibonacci numbers (1)
- Field programmable gate arrays (1)
- Finite automata (1)
- Flip-flops (1)
- Forgetting (1)
- Forschungsdatenmanagement (1)
- Freshmen (1)
- Function (1)
- Fundamental Ideas (1)
- GERBIL (1)
- Gesture input (1)
- Graphensuche (1)
- Green computing (1)
- Grounded theory (1)
- H.264 (1)
- Hairpin completions (1)
- Hairpin reductions (1)
- Hardware accelerator (1)
- Heat diffusion (1)
- Hierarchically configurable mask register (1)
- Histograms (1)
- Hochschul-Cloud (1)
- Hochschullehre (1)
- Https traffic (1)
- Human Factors (1)
- Hurricane Sandy (1)
- ICT Competence (1)
- ICT competencies (1)
- ICT skills (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)
- Inference (1)
- Informatics (1)
- Informatikstudium (1)
- Information federation (1)
- Information integration (1)
- Information retrieval (1)
- Information security (1)
- Innovation (1)
- Inquiry-based Learning (1)
- Insurance industry (1)
- Integrated circuit modeling (1)
- Interaktivität (1)
- Interface design (1)
- Internet of Things (1)
- Job monitoring (1)
- Job submission (1)
- Kernel (1)
- Kernelization (1)
- Key Competencies (1)
- Key input (1)
- Klausellernen (1)
- Knowledge representation (1)
- Kompetenzerwerb (1)
- L systems (1)
- LBA problem (1)
- LMS (1)
- Landmark visibility (1)
- Learners (1)
- Learning Fields (1)
- Learning ecology (1)
- Learning interfaces development (1)
- Learning with ICT (1)
- Lehrer*innenbildung (1)
- Lern-App (1)
- Lernaufgaben (1)
- Lernmotivation (1)
- Literature mining (1)
- Load Balancing (1)
- Localization (1)
- Location awareness (1)
- Logarithm (1)
- Logic programming (1)
- Low Latency (1)
- Lower Secondary Level (1)
- Loyalty (1)
- MOOCs (1)
- MQTT (1)
- Machine Learning (1)
- Markov processes (1)
- Masking of X-values (1)
- Massive Open Online Courses (1)
- Measurement (1)
- Media in education (1)
- Meta-Programming (1)
- Metric learning (1)
- Minimal perturbation problems (1)
- Mobile App (1)
- Mobile application (1)
- Mobile devices (1)
- Mobile learning (1)
- Model checking (1)
- Modeling (1)
- Modelling (1)
- Multi-objective optimization (1)
- Multi-sided platforms (1)
- Multiple interpretation scheme (1)
- Music Technology (1)
- N-temperature model (1)
- NUI (1)
- Nash equilibrium (1)
- Natural Science Education (1)
- Natural language processing (1)
- Natural ventilation (1)
- Network (1)
- Network security (1)
- Neural networks (1)
- NoSQL (1)
- Non-Monotonic (1)
- Nonmonotonic reasoning (1)
- Norway (1)
- Novice programmers (1)
- OCCI (1)
- OSSE (1)
- OpenOLAT (1)
- Operation problem (1)
- Optimization (1)
- Parallel SAT solving (1)
- Parallel job execution time estimation (1)
- Partizipation (1)
- Pedagogical content knowledge (1)
- Pedagogical issues (1)
- Pedestrian navigation (1)
- Performance Evaluation (1)
- Personalization (1)
- Persönliche Lernumgebung (1)
- Pervasive computing (1)
- Pervasive game (1)
- Pervasive learning (1)
- Physical Science (1)
- Planar tactile display (1)
- Polarization (1)
- Preference Handling (1)
- Preprocessing (1)
- Problem Solving (1)
- Process model analysis (1)
- Product lifecycle management (1)
- Programming (1)
- Programming by optimization (1)
- Prototyping (1)
- REST (1)
- RSA triangle (1)
- Random access memory (1)
- Ranking (1)
- Reasoning (1)
- Recommendations for CS-Curricula in Higher Education (1)
- Region of Interest (1)
- Relevanz (1)
- Reversibility (1)
- SAT (1)
- SOA (1)
- SWOT (1)
- SaaSAbstract (1)
- Scalability (1)
- Scale-invariant feature transform (SIFT) (1)
- Scientific images (1)
- Screen reader (1)
- Seamless learning (1)
- Search problems (1)
- Security (1)
- Semantic data (1)
- Semantic web (1)
- Semilinearity property (1)
- Sensors (1)
- Sequence embeddings (1)
- Service orientation (1)
- Sharing (1)
- Signal processing (1)
- Signaling transduction networks (1)
- Simulations (1)
- Single event effect (1)
- Single event upsets (1)
- Single-event transient (SET) (1)
- Small Private Online Courses (1)
- Social (1)
- Splicing (1)
- Splicing processor (1)
- Statistical relational learning (1)
- Stochastic relational process (1)
- Strong equivalence (1)
- Structural equation modeling (1)
- Studentenjobs (1)
- Studienabbrecher (1)
- Studiendauer (1)
- Systems biology (1)
- Systems of parallel communicating (1)
- TMR (1)
- TPACK (1)
- Tasks (1)
- Teacher perceptions (1)
- Teachers (1)
- Teaching information security (1)
- Technology proficiency (1)
- Terminology (1)
- Tests (1)
- Theorembeweisen (1)
- Theory formation (1)
- Thermoelasticity (1)
- Time series (1)
- Tools (1)
- Tracking (1)
- Traffic data (1)
- Tree decomposition (1)
- Treewidth (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)
- Unary languages (1)
- Unifikation (1)
- Uniform Access Principle (1)
- Usability testing (1)
- User Experience (1)
- User submission pattern (1)
- User-centred design (1)
- Value network (1)
- Verification (1)
- Visual metaphor (1)
- Vocational Education (1)
- Weiterbildung (1)
- Wireless Sensor Networks (1)
- Word embeddings (1)
- X-masking (1)
- X-values (1)
- Young People (1)
- abstraction (1)
- accepting grammars (1)
- action and change (1)
- activity (1)
- acute liver failure (1)
- acyclicity properties (1)
- adversarial classification (1)
- algorithm schedules (1)
- algorithms (1)
- analogical thinking (1)
- analysis (1)
- anti-cancer drugs (1)
- anxiety (1)
- approximate model counting (1)
- architecture (1)
- argument mining (1)
- arousal (1)
- artistic rendering (1)
- asynchrounous design (1)
- autism (1)
- automata (1)
- automated guided vehicle routing (1)
- automated planning (1)
- automatic feedback (1)
- behavioral abstraction (1)
- belief merging (1)
- belief revision (1)
- benchmark (1)
- bibliometric analysis (1)
- binary representation (1)
- binary search (1)
- block representation (1)
- bootstrapping (1)
- brain-computer interface (1)
- bundled data (1)
- camera sensor (1)
- car assembly operations (1)
- cellular automata (1)
- circuit Faults (1)
- citation analysis (1)
- classroom language (1)
- click controller (1)
- clocks (1)
- co-citation analysis (1)
- co-occurrence analysis (1)
- code generation (1)
- cognitive modifiability (1)
- coherence relation (1)
- collaborative learning (1)
- combinatorial optimization problems (1)
- combined task and motion planning (1)
- common spatial patterns (1)
- competence (1)
- competencies (1)
- competency (1)
- competition (1)
- complexity (1)
- compliance (1)
- comprehension (1)
- computer science teachers (1)
- computer vision (1)
- concession (1)
- concurrent checking (1)
- conductive argument (1)
- connective (1)
- consistency (1)
- consistency checking (1)
- consistency measures (1)
- context-free grammar (1)
- context-sensitive (1)
- contrast (1)
- controlled vocabularies (1)
- corpus analysis (1)
- correlated errors (1)
- course timetabling (1)
- craters (1)
- crop (1)
- cs4fn (1)
- curriculum theory (1)
- decidability questions (1)
- declarative problem solving (1)
- deep learning (1)
- deep neural networks (1)
- deep residual networks (1)
- degree of non-context-freeness (1)
- degree of non-regularity (1)
- degree of non-regulation (1)
- depression (1)
- design flow (1)
- determinism (1)
- detrending (1)
- developmental systems (1)
- diagnosis (1)
- didactics (1)
- didaktisches Konzept (1)
- digitale Bildung (1)
- digitale Medien (1)
- digitally-enabled pedagogies (1)
- divide and conquer (1)
- domain-specific APIs (1)
- drug discovery (1)
- drug-sensitivity prediction (1)
- dynamic service binding (1)
- e-mentoring (1)
- eLectures (1)
- economic ripples (1)
- edge computing (1)
- education and public policy (1)
- educational programming (1)
- educational systems (1)
- educational timetabling (1)
- edutainment (1)
- embedded systems (1)
- emission factor (1)
- endothelin (1)
- endothelin-converting enzyme (1)
- ensemble kalman filter (1)
- ensemble methods (1)
- environments (1)
- error propagation (1)
- evaluation (1)
- event-related desynchronization (1)
- evolution (1)
- exponentiation (1)
- external ambiguity (1)
- extreme weather (1)
- face tracking (1)
- facial expression (1)
- fault tolerance (1)
- field-programmable gate array (1)
- finite model computation (1)
- finite state sequential transducers (1)
- firmware update (1)
- formal (1)
- formal argumentation systems (1)
- fun (1)
- gap-filling (1)
- geovisualization (1)
- gradient boosting (1)
- grammar (1)
- graph-search (1)
- greenhouse gas (1)
- hardware accelerator (1)
- hardware architecture (1)
- high school (1)
- higher (1)
- hybrid solving (1)
- ice harboring (1)
- image classification (1)
- image processing (1)
- image recognition (1)
- impacts (1)
- incremental SVM (1)
- informal and formal learning (1)
- informal logic (1)
- informatics (1)
- informatics education (1)
- information flow control (1)
- innovation (1)
- interactive course (1)
- interactive workshop (1)
- internal ambiguity (1)
- intrusion detection (1)
- key competences in physical computing (1)
- key competencies (1)
- kidney cancer (1)
- kinaesthetic teaching (1)
- klinisch-praktischer Unterricht (1)
- knowledge representation and nonmonotonic reasoning (1)
- knowledge representation and reasoning (1)
- latches (1)
- learning (1)
- leftmost derivations (1)
- lesson planning (1)
- lesson preparation (1)
- linear programming (1)
- logic programming (1)
- logic-based modeling (1)
- loop formulas (1)
- loose programming (1)
- loss propagation (1)
- lunar exploration (1)
- machine learning (1)
- machine learning algorithms (1)
- manipulation planning (1)
- measure development (1)
- media (1)
- mediated learning experience (1)
- metabolic network (1)
- metabolism (1)
- metabolomics (1)
- metadata (1)
- metastasis (1)
- mobile learning (1)
- mobile technologies and apps (1)
- mobiles Lernen (1)
- natural disasters (1)
- natural language generation (1)
- neighborhood (1)
- networks (1)
- neural networks (1)
- neutral endopeptidase (1)
- nonphotorealistic rendering (NPR) (1)
- o-ambiguity (1)
- on-farm evaluation (1)
- open learning (1)
- operating system (1)
- organisational evolution (1)
- paper prototyping (1)
- parallel processing (1)
- parallel rewriting (1)
- parameter (1)
- parity aggregate operator (1)
- parsing (1)
- pdf forms (1)
- pedagogy (1)
- perception (1)
- perception differences (1)
- personal (1)
- personal response systems (1)
- philosophical foundation of informatics pedagogy (1)
- physical computing (1)
- physical computing tools (1)
- planning (1)
- plug-ins (1)
- policy evaluation (1)
- portfolio-based solving (1)
- pre-primary level (1)
- predictive models (1)
- premise acceptability (1)
- preprocessing (1)
- primary education (1)
- primary level (1)
- problem-solving (1)
- process model alignment (1)
- process modeling (1)
- professional development (1)
- program encodings (1)
- programmed grammars (1)
- programming (1)
- programming in context (1)
- projection (1)
- proof complexity (1)
- pruritus (1)
- quality of life (1)
- quantum (1)
- random forest (1)
- real arguments (1)
- real-time (1)
- real-time mapping (1)
- reference (1)
- referential effectiveness (1)
- regression (1)
- regular language (1)
- reliability (1)
- reliability analysis (1)
- resources (1)
- restricted parallelism (1)
- satisfiability (1)
- secondary computer science education (1)
- secondary education (1)
- selective fault tolerance (1)
- self-adaptive multiprocessing system (1)
- self-checking (1)
- self-efficacy (1)
- semantic web (1)
- simplicity (1)
- single event upset (1)
- single event upsets (1)
- single-trial-analysis (1)
- site-specific weed management (1)
- sleep quality (1)
- smart farming (1)
- social media (1)
- soft errors (1)
- solar particle event (1)
- space missions (1)
- stable model semantics (1)
- state complexity (1)
- static analysis (1)
- static prediction games (1)
- strong equivalence (1)
- student activation (1)
- student experience (1)
- student perceptions (1)
- students’ conceptions (1)
- students’ knowledge (1)
- sufficiency (1)
- suicidal ideations (1)
- supply chains (1)
- support system (1)
- support vector machines (1)
- tableau calculi (1)
- teacher competencies (1)
- teacher training (1)
- teaching (1)
- teaching informatics in general education (1)
- technical notes and rapid communications (1)
- technische Rahmenbedingungen (1)
- tele-teaching (1)
- test response compaction (1)
- theorem (1)
- theory of computation (1)
- timing (1)
- tracing (1)
- transient Faults (1)
- transient analysis (1)
- triangulated irregular networks (1)
- triple modular redundancy (1)
- unfounded sets (1)
- unification (1)
- user experience (1)
- user-centred (1)
- verification (1)
- video annotation (1)
- virtual mobility (1)
- virtual reality (1)
- wheat crops (1)
- work productivity (1)
- xAPI (1)
- yellow rust (1)
- ‘unplugged’ computing (1)
Institute
- Institut für Informatik und Computational Science (672)
- Institut für Physik und Astronomie (2)
- eLiS - E-Learning in Studienbereichen (2)
- Department Erziehungswissenschaft (1)
- Department Linguistik (1)
- Extern (1)
- Historisches Institut (1)
- Universitätsbibliothek (1)
- Zentrum für Qualitätsentwicklung in Lehre und Studium (ZfQ) (1)
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.
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.
The concept of Linked Data has made its entrance in the cultural heritage sector due to its potential use for the integration of heterogeneous collections and deriving additional value out of existing metadata. However, practitioners and researchers alike need a better understanding of what outcome they can reasonably expect of the reconciliation process between their local metadata and established controlled vocabularies which are already a part of the Linked Data cloud. This paper offers an in-depth analysis of how a locally developed vocabulary can be successfully reconciled with the Library of Congress Subject Headings (LCSH) and the Arts and Architecture Thesaurus (AAT) through the help of a general-purpose tool for interactive data transformation (OpenRefine). Issues negatively affecting the reconciliation process are identified and solutions are proposed in order to derive maximum value from existing metadata and controlled vocabularies in an automated manner.
fundamental challenge for product-lifecycle management in collaborative value networks is to utilize the vast amount of product information available from heterogeneous sources in order to improve business analytics, decision support, and processes. This becomes even more challenging if those sources are distributed across multiple organizations. Federations of semantic information services, combining service-orientation and semantic technologies, provide a promising solution for this problem. However, without proper measures to establish information security, companies will be reluctant to join an information federation, which could lead to serious adoption barriers.
Following the design science paradigm, this paper presents general objectives and a process for designing a secure federation of semantic information services. Furthermore, new as well as established security measures are discussed. Here, our contributions include an access-control enforcement system for semantic information services and a process for modeling access-control policies across organizations. In addition, a comprehensive security architecture is presented. An implementation of the architecture in the context of an application scenario and several performance experiments demonstrate the practical viability of our approach.
This paper surveys the field of nonphotorealistic rendering (NPR), focusing on techniques for transforming 2D input (images and video) into artistically stylized renderings. We first present a taxonomy of the 2D NPR algorithms developed over the past two decades, structured according to the design characteristics and behavior of each technique. We then describe a chronology of development from the semiautomatic paint systems of the early nineties, through to the automated painterly rendering systems of the late nineties driven by image gradient analysis. Two complementary trends in the NPR literature are then addressed, with reference to our taxonomy. First, the fusion of higher level computer vision and NPR, illustrating the trends toward scene analysis to drive artistic abstraction and diversity of style. Second, the evolution of local processing approaches toward edge-aware filtering for real-time stylization of images and video. The survey then concludes with a discussion of open challenges for 2D NPR identified in recent NPR symposia, including topics such as user and aesthetic evaluation.
We introduce formal proof systems based on tableau methods for analyzing computations in Answer Set Programming (ASP). Our approach furnishes fine-grained instruments for characterizing operations as well as strategies of ASP solvers. The granularity is detailed enough to capture a variety of propagation and choice methods of algorithms used for ASP solving, also incorporating SAT-based and conflict-driven learning approaches to some extent. This provides us with a uniform setting for identifying and comparing fundamental properties of ASP solving approaches. In particular, we investigate their proof complexities and show that the run-times of best-case computations can vary exponentially between different existing ASP solvers. Apart from providing a framework for comparing ASP solving approaches, our characterizations also contribute to their understanding by pinning down the constitutive atomic operations. Furthermore, our framework is flexible enough to integrate new inference patterns, and so to study their relation to existing ones. To this end, we generalize our approach and provide an extensible basis aiming at a modular incorporation of additional language constructs. This is exemplified by augmenting our basic tableau methods with cardinality constraints and disjunctions.
We address the problem of belief change in (nonmonotonic) logic programming under answer set semantics. Our formal techniques are analogous to those of distance-based belief revision in propositional logic. In particular, we build upon the model theory of logic programs furnished by SE interpretations, where an SE interpretation is a model of a logic program in the same way that a classical interpretation is a model of a propositional formula. Hence we extend techniques from the area of belief revision based on distance between models to belief change in logic programs.
We first consider belief revision: for logic programs P and Q, the goal is to determine a program R that corresponds to the revision of P by Q, denoted P * Q. We investigate several operators, including (logic program) expansion and two revision operators based on the distance between the SE models of logic programs. It proves to be the case that expansion is an interesting operator in its own right, unlike in classical belief revision where it is relatively uninteresting. Expansion and revision are shown to satisfy a suite of interesting properties; in particular, our revision operators satisfy all or nearly all of the AGM postulates for revision.
We next consider approaches for merging a set of logic programs, P-1,...,P-n. Again, our formal techniques are based on notions of relative distance between the SE models of the logic programs. Two approaches are examined. The first informally selects for each program P-i those models of P-i that vary the least from models of the other programs. The second approach informally selects those models of a program P-0 that are closest to the models of programs P-1,...,P-n. In this case, P-0 can be thought of as a set of database integrity constraints. We examine these operators with regards to how they satisfy relevant postulate sets.
Last, we present encodings for computing the revision as well as the merging of logic programs within the same logic programming framework. This gives rise to a direct implementation of our approach in terms of off-the-shelf answer set solvers. These encodings also reflect the fact that our change operators do not increase the complexity of the base formalism.