@book{AbedjanNaumann2011, author = {Abedjan, Ziawasch and Naumann, Felix}, title = {Advancing the discovery of unique column combinations}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-148-6}, issn = {1613-5652}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53564}, publisher = {Universit{\"a}t Potsdam}, pages = {25}, year = {2011}, abstract = {Unique column combinations of a relational database table are sets of columns that contain only unique values. Discovering such combinations is a fundamental research problem and has many different data management and knowledge discovery applications. Existing discovery algorithms are either brute force or have a high memory load and can thus be applied only to small datasets or samples. In this paper, the wellknown GORDIAN algorithm and "Apriori-based" algorithms are compared and analyzed for further optimization. We greatly improve the Apriori algorithms through efficient candidate generation and statistics-based pruning methods. A hybrid solution HCAGORDIAN combines the advantages of GORDIAN and our new algorithm HCA, and it significantly outperforms all previous work in many situations.}, language = {en} } @book{KleineHirschfeldBracha2011, author = {Kleine, Matthias and Hirschfeld, Robert and Bracha, Gilad}, title = {An abstraction for version control systems}, series = {Technische Berichte des Hasso-Plattner-Instituts f{\"u}r Softwaresystemtechnik an der Universit{\"a}t Potsdam}, journal = {Technische Berichte des Hasso-Plattner-Instituts f{\"u}r Softwaresystemtechnik an der Universit{\"a}t Potsdam}, number = {54}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-158-5}, issn = {1613-5652}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-55629}, publisher = {Universit{\"a}t Potsdam}, pages = {77}, year = {2011}, abstract = {Versionsverwaltungssysteme (VCS) erm{\"o}glichen es Entwicklern, {\"A}nderungen an Softwareartifakten zu verwalten. VCS werden mit Hilfe einer Vielzahl verschiedener Werkzeuge bedient, wie z.\,B. graphische Front-ends oder Kommandozeilenwerkzeuge. Es ist w{\"u}nschenswert mit einzelnen solcher Werkzeuge unterschiedliche VCS bedienen zu k{\"o}nnen. Bislang hat sich jedoch keine Abstraktion f{\"u}r Versionsverwaltungssysteme durchgesetzt, mit deren Hilfe solche Werkzeuge erstellt werden k{\"o}nnen. Stattdessen implementieren Werkzeuge zur Interaktion mit mehreren VCS ad-hoc L{\"o}sungen. Diese Masterarbeit stellt Pur vor, eine Abstraktion {\"u}ber Versionsverwaltungskonzepte. Mit Hilfe von Pur k{\"o}nnen Anwendungsprogramme entwickelt werden, die mit mehreren Versionsverwaltungssystemen interagieren k{\"o}nnen. Im Rahmen dieser Arbeit wird eine Implementierung dieser Abstraktion bereitgestellt und mit Hilfe eines Anwendungsprogramms validiert.}, language = {en} } @phdthesis{Wist2011, author = {Wist, Dominic}, title = {Attacking complexity in logic synthesis of asynchronous circuits}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-59706}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Most of the microelectronic circuits fabricated today are synchronous, i.e. they are driven by one or several clock signals. Synchronous circuit design faces several fundamental challenges such as high-speed clock distribution, integration of multiple cores operating at different clock rates, reduction of power consumption and dealing with voltage, temperature, manufacturing and runtime variations. Asynchronous or clockless design plays a key role in alleviating these challenges, however the design and test of asynchronous circuits is much more difficult in comparison to their synchronous counterparts. A driving force for a widespread use of asynchronous technology is the availability of mature EDA (Electronic Design Automation) tools which provide an entire automated design flow starting from an HDL (Hardware Description Language) specification yielding the final circuit layout. Even though there was much progress in developing such EDA tools for asynchronous circuit design during the last two decades, the maturity level as well as the acceptance of them is still not comparable with tools for synchronous circuit design. In particular, logic synthesis (which implies the application of Boolean minimisation techniques) for the entire system's control path can significantly improve the efficiency of the resulting asynchronous implementation, e.g. in terms of chip area and performance. However, logic synthesis, in particular for asynchronous circuits, suffers from complexity problems. Signal Transitions Graphs (STGs) are labelled Petri nets which are a widely used to specify the interface behaviour of speed independent (SI) circuits - a robust subclass of asynchronous circuits. STG decomposition is a promising approach to tackle complexity problems like state space explosion in logic synthesis of SI circuits. The (structural) decomposition of STGs is guided by a partition of the output signals and generates a usually much smaller component STG for each partition member, i.e. a component STG with a much smaller state space than the initial specification. However, decomposition can result in component STGs that in isolation have so-called irreducible CSC conflicts (i.e. these components are not SI synthesisable anymore) even if the specification has none of them. A new approach is presented to avoid such conflicts by introducing internal communication between the components. So far, STG decompositions are guided by the finest output partitions, i.e. one output per component. However, this might not yield optimal circuit implementations. Efficient heuristics are presented to determine coarser partitions leading to improved circuits in terms of chip area. For the new algorithms correctness proofs are given and their implementations are incorporated into the decomposition tool DESIJ. The presented techniques are successfully applied to some benchmarks - including 'real-life' specifications arising in the context of control resynthesis - which delivered promising results.}, language = {en} } @misc{DurzinskyMarwanOstrowskietal.2011, author = {Durzinsky, Markus and Marwan, Wolfgang and Ostrowski, Max and Schaub, Torsten H. and Wagler, Annegret}, title = {Automatic network reconstruction using ASP}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {560}, issn = {1866-8372}, doi = {10.25932/publishup-41241}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-412419}, pages = {18}, year = {2011}, abstract = {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.}, language = {en} } @phdthesis{Weidlich2011, author = {Weidlich, Matthias}, title = {Behavioural profiles : a relational approach to behaviour consistency}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-55590}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Business Process Management (BPM) emerged as a means to control, analyse, and optimise business operations. Conceptual models are of central importance for BPM. Most prominently, process models define the behaviour that is performed to achieve a business value. In essence, a process model is a mapping of properties of the original business process to the model, created for a purpose. Different modelling purposes, therefore, result in different models of a business process. Against this background, the misalignment of process models often observed in the field of BPM is no surprise. Even if the same business scenario is considered, models created for strategic decision making differ in content significantly from models created for process automation. Despite their differences, process models that refer to the same business process should be consistent, i.e., free of contradictions. Apparently, there is a trade-off between strictness of a notion of consistency and appropriateness of process models serving different purposes. Existing work on consistency analysis builds upon behaviour equivalences and hierarchical refinements between process models. Hence, these approaches are computationally hard and do not offer the flexibility to gradually relax consistency requirements towards a certain setting. This thesis presents a framework for the analysis of behaviour consistency that takes a fundamentally different approach. As a first step, an alignment between corresponding elements of related process models is constructed. Then, this thesis conducts behavioural analysis grounded on a relational abstraction of the behaviour of a process model, its behavioural profile. Different variants of these profiles are proposed, along with efficient computation techniques for a broad class of process models. Using behavioural profiles, consistency of an alignment between process models is judged by different notions and measures. The consistency measures are also adjusted to assess conformance of process logs that capture the observed execution of a process. Further, this thesis proposes various complementary techniques to support consistency management. It elaborates on how to implement consistent change propagation between process models, addresses the exploration of behavioural commonalities and differences, and proposes a model synthesis for behavioural profiles.}, language = {en} } @phdthesis{Smirnov2011, author = {Smirnov, Sergey}, title = {Business process model abstraction}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-60258}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Business process models are used within a range of organizational initiatives, where every stakeholder has a unique perspective on a process and demands the respective model. As a consequence, multiple process models capturing the very same business process coexist. Keeping such models in sync is a challenge within an ever changing business environment: once a process is changed, all its models have to be updated. Due to a large number of models and their complex relations, model maintenance becomes error-prone and expensive. Against this background, business process model abstraction emerged as an operation reducing the number of stored process models and facilitating model management. Business process model abstraction is an operation preserving essential process properties and leaving out insignificant details in order to retain information relevant for a particular purpose. Process model abstraction has been addressed by several researchers. The focus of their studies has been on particular use cases and model transformations supporting these use cases. This thesis systematically approaches the problem of business process model abstraction shaping the outcome into a framework. We investigate the current industry demand in abstraction summarizing it in a catalog of business process model abstraction use cases. The thesis focuses on one prominent use case where the user demands a model with coarse-grained activities and overall process ordering constraints. We develop model transformations that support this use case starting with the transformations based on process model structure analysis. Further, abstraction methods considering the semantics of process model elements are investigated. First, we suggest how semantically related activities can be discovered in process models-a barely researched challenge. The thesis validates the designed abstraction methods against sets of industrial process models and discusses the method implementation aspects. Second, we develop a novel model transformation, which combined with the related activity discovery allows flexible non-hierarchical abstraction. In this way this thesis advocates novel model transformations that facilitate business process model management and provides the foundations for innovative tool support.}, language = {en} } @misc{GebserKaminskiSchaub2011, author = {Gebser, Martin and Kaminski, Roland and Schaub, Torsten H.}, title = {Complex optimization in answer set programming}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {554}, issn = {1866-8372}, doi = {10.25932/publishup-41243}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-412436}, pages = {19}, year = {2011}, abstract = {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.}, language = {en} } @phdthesis{Bordihn2011, author = {Bordihn, Henning}, title = {Contributions to the syntactical analysis beyond context-freeness}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-59719}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Parsability approaches of several grammar formalisms generating also non-context-free languages are explored. Chomsky grammars, Lindenmayer systems, grammars with controlled derivations, and grammar systems are treated. Formal properties of these mechanisms are investigated, when they are used as language acceptors. Furthermore, cooperating distributed grammar systems are restricted so that efficient deterministic parsing without backtracking becomes possible. For this class of grammar systems, the parsing algorithm is presented and the feature of leftmost derivations is investigated in detail.}, language = {en} } @book{HauptMarrHirschfeld2011, author = {Haupt, Michael and Marr, Stefan and Hirschfeld, Robert}, title = {CSOM/PL : a virtual machine product line}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-134-9}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52332}, publisher = {Universit{\"a}t Potsdam}, pages = {26}, year = {2011}, abstract = {CSOM/PL is a software product line (SPL) derived from applying multi-dimensional separation of concerns (MDSOC) techniques to the domain of high-level language virtual machine (VM) implementations. For CSOM/PL, we modularised CSOM, a Smalltalk VM implemented in C, using VMADL (virtual machine architecture description language). Several features of the original CSOM were encapsulated in VMADL modules and composed in various combinations. In an evaluation of our approach, we show that applying MDSOC and SPL principles to a domain as complex as that of VMs is not only feasible but beneficial, as it improves understandability, maintainability, and configurability of VM implementations without harming performance.}, language = {en} } @book{MeyerSmirnovWeske2011, author = {Meyer, Andreas and Smirnov, Sergey and Weske, Mathias}, title = {Data in business processes}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-144-8}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53046}, publisher = {Universit{\"a}t Potsdam}, pages = {40}, year = {2011}, abstract = {Process and data are equally important for business process management. Process data is especially relevant in the context of automated business processes, process controlling, and representation of organizations' core assets. One can discover many process modeling languages, each having a specific set of data modeling capabilities and the level of data awareness. The level of data awareness and data modeling capabilities vary significantly from one language to another. This paper evaluates several process modeling languages with respect to the role of data. To find a common ground for comparison, we develop a framework, which systematically organizes process- and data-related aspects of the modeling languages elaborating on the data aspects. Once the framework is in place, we compare twelve process modeling languages against it. We generalize the results of the comparison and identify clusters of similar languages with respect to data awareness.}, language = {de} }