Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-32628 Dissertation Appeltauer, Malte Extending Context-oriented Programming to New Application Domains: Run-time Adaptation Support for Java Potsdam 2012 157 S. Institut für Informatik und Computational Science OPUS4-33644 Dissertation Bog, Anja Benchmarking composite transaction and analytical processing systems : the creation of a mixed workload benchmark and its application in evaluating the impact of database schema optimizations in mixed workload scenarios Potsdam 2012 173 S. Institut für Informatik und Computational Science OPUS4-35974 Wissenschaftlicher Artikel Bordihn, Henning; Kutrib, Martin; Malcher, Andreas On the computational capacity of parallel communicating finite automata 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. Singapore World Scientific 2012 20 International journal of foundations of computer science 23 3 713 732 10.1142/S0129054112500062 Institut für Informatik und Computational Science OPUS4-33144 Dissertation Broß, Justus F. M. Understanding and leveraging the social physics of the blogosphere Potsdam 2012 200 S. Institut für Informatik und Computational Science OPUS4-5964 Dissertation Brückner, Michael Prediction games : machine learning in the presence of an adversary In many applications one is faced with the problem of inferring some functional relation between input and output variables from given data. Consider, for instance, the task of email spam filtering where one seeks to find a model which automatically assigns new, previously unseen emails to class spam or non-spam. Building such a predictive model based on observed training inputs (e.g., emails) with corresponding outputs (e.g., spam labels) is a major goal of machine learning. Many learning methods assume that these training data are governed by the same distribution as the test data which the predictive model will be exposed to at application time. That assumption is violated when the test data are generated in response to the presence of a predictive model. This becomes apparent, for instance, in the above example of email spam filtering. Here, email service providers employ spam filters and spam senders engineer campaign templates such as to achieve a high rate of successful deliveries despite any filters. Most of the existing work casts such situations as learning robust models which are unsusceptible against small changes of the data generation process. The models are constructed under the worst-case assumption that these changes are performed such to produce the highest possible adverse effect on the performance of the predictive model. However, this approach is not capable to realistically model the true dependency between the model-building process and the process of generating future data. We therefore establish the concept of prediction games: We model the interaction between a learner, who builds the predictive model, and a data generator, who controls the process of data generation, as an one-shot game. The game-theoretic framework enables us to explicitly model the players' interests, their possible actions, their level of knowledge about each other, and the order at which they decide for an action. We model the players' interests as minimizing their own cost function which both depend on both players' actions. The learner's action is to choose the model parameters and the data generator's action is to perturbate the training data which reflects the modification of the data generation process with respect to the past data. We extensively study three instances of prediction games which differ regarding the order in which the players decide for their action. We first assume that both player choose their actions simultaneously, that is, without the knowledge of their opponent's decision. We identify conditions under which this Nash prediction game has a meaningful solution, that is, a unique Nash equilibrium, and derive algorithms that find the equilibrial prediction model. As a second case, we consider a data generator who is potentially fully informed about the move of the learner. This setting establishes a Stackelberg competition. We derive a relaxed optimization criterion to determine the solution of this game and show that this Stackelberg prediction game generalizes existing prediction models. Finally, we study the setting where the learner observes the data generator's action, that is, the (unlabeled) test data, before building the predictive model. As the test data and the training data may be governed by differing probability distributions, this scenario reduces to learning under covariate shift. We derive a new integrated as well as a two-stage method to account for this data set shift. In case studies on email spam filtering we empirically explore properties of all derived models as well as several existing baseline methods. We show that spam filters resulting from the Nash prediction game as well as the Stackelberg prediction game in the majority of cases outperform other existing baseline methods. Potsdam Universitätsverlag Potsdam 2012 x, 121 978-3-86956-203-2 urn:nbn:de:kobv:517-opus-60375 Institut für Informatik und Computational Science OPUS4-35662 Wissenschaftlicher Artikel Brückner, Michael; Kanzow, Christian; Scheffer, Tobias Static prediction games for adversarial learning problems 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. Cambridge, Mass. Microtome Publishing 2012 38 Journal of machine learning research 13 2617 2654 Institut für Informatik und Computational Science OPUS4-47669 misc Ebert, Birgitta E.; Lamprecht, Anna-Lena; Steffen, Bernhard; Blank, Lars M. Flux-P 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. 2012 21 Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe 1054 872 890 urn:nbn:de:kobv:517-opus4-476696 10.25932/publishup-47669 Institut für Informatik und Computational Science OPUS4-35482 Wissenschaftlicher Artikel Fabian, Benjamin; Kunz, Steffen; Konnegen, Marcel; Müller, Sebastian; Günther, Oliver Access control for semantic data federations in industrial product-lifecycle management 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. Amsterdam Elsevier 2012 11 Computers in industry : an international, application oriented research journal 63 9 930 940 10.1016/j.compind.2012.08.015 Institut für Informatik und Computational Science OPUS4-33869 Wissenschaftlicher Artikel Gabrysiak, Gregor; Giese, Holger; Seibel, Andreas Towards next-generation design thinking II : virtual muti-user software prototypes 2012 Institut für Informatik und Computational Science OPUS4-35754 Wissenschaftlicher Artikel Gebser, Martin; Kaufmann, Benjamin; Schaub, Torsten H. Conflict-driven answer set solving: From theory to practice 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. Amsterdam Elsevier 2012 38 Artificial intelligence 187 8 52 89 10.1016/j.artint.2012.04.001 Institut für Informatik und Computational Science OPUS4-35776 Wissenschaftlicher Artikel Gebser, Martin; Kaufmann, Benjamin; Schaub, Torsten H. Multi-threaded ASP solving with clasp 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. New York Cambridge Univ. Press 2012 21 Theory and practice of logic programming 12 8 525 545 10.1017/S1471068412000166 Institut für Informatik und Computational Science OPUS4-33868 Wissenschaftlicher Artikel Gericke, Lutz; Gumienny, Raja; Meinel, Christoph Tele-board : folow the traces of your design process history 2012 Institut für Informatik und Computational Science OPUS4-6201 Dissertation Glander, Tassilo Multi-scale representations of virtual 3D city models Virtual 3D city and landscape models are the main subject investigated in this thesis. They digitally represent urban space and have many applications in different domains, e.g., simulation, cadastral management, and city planning. Visualization is an elementary component of these applications. Photo-realistic visualization with an increasingly high degree of detail leads to fundamental problems for comprehensible visualization. A large number of highly detailed and textured objects within a virtual 3D city model may create visual noise and overload the users with information. Objects are subject to perspective foreshortening and may be occluded or not displayed in a meaningful way, as they are too small. In this thesis we present abstraction techniques that automatically process virtual 3D city and landscape models to derive abstracted representations. These have a reduced degree of detail, while essential characteristics are preserved. After introducing definitions for model, scale, and multi-scale representations, we discuss the fundamentals of map generalization as well as techniques for 3D generalization. The first presented technique is a cell-based generalization of virtual 3D city models. It creates abstract representations that have a highly reduced level of detail while maintaining essential structures, e.g., the infrastructure network, landmark buildings, and free spaces. The technique automatically partitions the input virtual 3D city model into cells based on the infrastructure network. The single building models contained in each cell are aggregated to abstracted cell blocks. Using weighted infrastructure elements, cell blocks can be computed on different hierarchical levels, storing the hierarchy relation between the cell blocks. Furthermore, we identify initial landmark buildings within a cell by comparing the properties of individual buildings with the aggregated properties of the cell. For each block, the identified landmark building models are subtracted using Boolean operations and integrated in a photo-realistic way. Finally, for the interactive 3D visualization we discuss the creation of the virtual 3D geometry and their appearance styling through colors, labeling, and transparency. We demonstrate the technique with example data sets. Additionally, we discuss applications of generalization lenses and transitions between abstract representations. The second technique is a real-time-rendering technique for geometric enhancement of landmark objects within a virtual 3D city model. Depending on the virtual camera distance, landmark objects are scaled to ensure their visibility within a specific distance interval while deforming their environment. First, in a preprocessing step a landmark hierarchy is computed, this is then used to derive distance intervals for the interactive rendering. At runtime, using the virtual camera distance, a scaling factor is computed and applied to each landmark. The scaling factor is interpolated smoothly at the interval boundaries using cubic Bézier splines. Non-landmark geometry that is near landmark objects is deformed with respect to a limited number of landmarks. We demonstrate the technique by applying it to a highly detailed virtual 3D city model and a generalized 3D city model. In addition we discuss an adaptation of the technique for non-linear projections and mobile devices. The third technique is a real-time rendering technique to create abstract 3D isocontour visualization of virtual 3D terrain models. The virtual 3D terrain model is visualized as a layered or stepped relief. The technique works without preprocessing and, as it is implemented using programmable graphics hardware, can be integrated with minimal changes into common terrain rendering techniques. Consequently, the computation is done in the rendering pipeline for each vertex, primitive, i.e., triangle, and fragment. For each vertex, the height is quantized to the nearest isovalue. For each triangle, the vertex configuration with respect to their isovalues is determined first. Using the configuration, the triangle is then subdivided. The subdivision forms a partial step geometry aligned with the triangle. For each fragment, the surface appearance is determined, e.g., depending on the surface texture, shading, and height-color-mapping. Flexible usage of the technique is demonstrated with applications from focus+context visualization, out-of-core terrain rendering, and information visualization. This thesis presents components for the creation of abstract representations of virtual 3D city and landscape models. Re-using visual language from cartography, the techniques enable users to build on their experience with maps when interpreting these representations. Simultaneously, characteristics of 3D geovirtual environments are taken into account by addressing and discussing, e.g., continuous scale, interaction, and perspective. 2012 urn:nbn:de:kobv:517-opus-64117 Institut für Informatik und Computational Science OPUS4-33653 Dissertation Grund, Martin Hyrise : a main memory hybrid database storage engine Potsdam 2012 175 S. Institut für Informatik und Computational Science OPUS4-33856 Wissenschaftlicher Artikel Gumienny, Raja; Gericke, Lutz; Wenzel, Matthias; Meinel, Christoph Tele-board in use : applying aq digital whiteboard system in different situations and setups 2012 978-3-642-31990-7 Institut für Informatik und Computational Science OPUS4-33854 Wissenschaftlicher Artikel Jobst, Birgit; Köppen, Eva; Lindberg, Tilmann; Moritz, Josephine; Rhinow, Holger; Meinel, Christoph The faith-factor in design thinking : creative confidence through education at the design thinking schools Potsdam and Standford? 2012 978-3-642-31990-7 Institut für Informatik und Computational Science OPUS4-33870 Wissenschaftlicher Artikel Kowark, Thomas; Uflacker, Matthias; Zeier, Alexander Towards a shared platform for virtual collaboration monotoring in design research 2012 Institut für Informatik und Computational Science OPUS4-33850 Buch (Monographie) Lerch, Alexander An introduction to audio content analysis : applications in signal processing and music informatics Hoboken, N.J Wiley 2012 248 S. 978-1-118-26682-3 10.1002/9781118393550 Institut für Informatik und Computational Science OPUS4-33871 Wissenschaftlicher Artikel Lindberg, Tilmann; Köppen, Eva; Rauth, Ingo; Meinel, Christoph On the perection, adoption and Implementation of design thinking in the IT industry 2012 Institut für Informatik und Computational Science OPUS4-33872 Wissenschaftlicher Artikel Luebbe, Alexander; Weske, Mathias Determining the effect of tangible business process modeling 2012 Institut für Informatik und Computational Science