@phdthesis{Luckow2009, author = {Luckow, Andr{\´e}}, title = {A dependable middleware for enhancing the fault tolerance of distributed computations in grid environments}, address = {Potsdam}, pages = {235 S.}, year = {2009}, language = {en} } @unpublished{Arnold2009, author = {Arnold, Holger}, title = {A linearized DPLL calculus with clause learning (2nd, revised version)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29080}, year = {2009}, abstract = {Many formal descriptions of DPLL-based SAT algorithms either do not include all essential proof techniques applied by modern SAT solvers or are bound to particular heuristics or data structures. This makes it difficult to analyze proof-theoretic properties or the search complexity of these algorithms. In this paper we try to improve this situation by developing a nondeterministic proof calculus that models the functioning of SAT algorithms based on the DPLL calculus with clause learning. This calculus is independent of implementation details yet precise enough to enable a formal analysis of realistic DPLL-based SAT algorithms.}, language = {en} } @article{LyTarkhanov2009, author = {Ly, Ibrahim and Tarkhanov, Nikolai Nikolaevich}, title = {A variational approach to the Cauchy problem for nonlinear elliptic differential equations}, issn = {0928-0219}, doi = {10.1515/Jiip.2009.037}, year = {2009}, abstract = {We discuss the relaxation of a class of nonlinear elliptic Cauchy problems with data on a piece S of the boundary surface by means of a variational approach known in the optimal control literature as "equation error method". By the Cauchy problem is meant any boundary value problem for an unknown function y in a domain X with the property that the data on S, if combined with the differential equations in X, allow one to determine all derivatives of y on S by means of functional equations. In the case of real analytic data of the Cauchy problem, the existence of a local solution near S is guaranteed by the Cauchy-Kovalevskaya theorem. We also admit overdetermined elliptic systems, in which case the set of those Cauchy data on S for which the Cauchy problem is solvable is very "thin". For this reason we discuss a variational setting of the Cauchy problem which always possesses a generalised solution.}, language = {en} } @article{LuckowJhaKimetal.2009, author = {Luckow, Andre and Jha, Shantenu and Kim, Joohyun and Merzky, Andre and Schnor, Bettina}, title = {Adaptive distributed replica-exchange simulations}, issn = {1364-503X}, doi = {10.1098/rsta.2009.0051}, year = {2009}, abstract = {Owing to the loose coupling between replicas, the replica-exchange (RE) class of algorithms should be able to benefit greatly from using as many resources as available. However, the ability to effectively use multiple distributed resources to reduce the time to completion remains a challenge at many levels. Additionally, an implementation of a pleasingly distributed algorithm such as replica-exchange, which is independent of infrastructural details, does not exist. This paper proposes an extensible and scalable framework based on Simple API for Grid Applications that provides a general-purpose, opportunistic mechanism to effectively use multiple resources in an infrastructure-independent way. By analysing the requirements of the RE algorithm and the challenges of implementing it on real production systems, we propose a new abstraction (BIGJOB), which forms the basis of the adaptive redistribution and effective scheduling of replicas.}, language = {en} } @article{WeickerWeicker2009, author = {Weicker, Nicole and Weicker, Karsten}, title = {Analyse des Kompetenzerwerbs im Softwarepraktikum}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {1}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29676}, pages = {93 -- 104}, year = {2009}, abstract = {Diese Arbeit enth{\"a}lt eine umfassende Analyse, wie der Kompetenzerwerb in einem einsemestrigen Softwarepraktikum vonstatten geht. Dabei steht neben der Frage, welche Kompetenzen besonders gut erworben wurden, der Einfluss von Vorwissen/-kompetenz im Mittelpunkt der Abhandlung. Auf dieser Basis werden einige grundlegende und konkrete Verbesserungsvorschl{\"a}ge erarbeitet, wie der breite Kompetenzerwerb beg{\"u}nstigt wird, d.h. m{\"o}glichst viele Studierende sich in einem breiten Kompetenzspektrum weiterentwickeln.}, language = {de} } @phdthesis{Schult2009, author = {Schult, Wolfgang}, title = {Architektur komponenten-basierter Systeme mit LOOM : Aspekte, Muster, Werkzeuge}, publisher = {Cuvillier}, address = {G{\"o}ttingen}, isbn = {978-3-86955-031-2}, pages = {217 S.}, year = {2009}, language = {de} } @article{BieniusaDegenHeideggeretal.2009, author = {Bieniusa, Annette and Degen, Markus and Heidegger, Phillip and Thiemann, Peter and Wehr, Stefan and Gasbichler, Martin and Crestani, Marcus and Klaeren, Herbert and Knauel, Eric and Sperber, Michael}, title = {Auf dem Weg zu einer robusten Programmierausbildung}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {1}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29655}, pages = {67 -- 79}, year = {2009}, abstract = {Die gelungene Durchf{\"u}hrung einer Vorlesung „Informatik I - Einf{\"u}hrung in die Programmierung" ist schwierig, trotz einer Vielfalt existierender Materialien und erprobter didaktischer Methoden. Gerade aufgrund dieser vielf{\"a}ltigen Auswahl hat sich bisher noch kein robustes Konzept durchgesetzt, das unabh{\"a}ngig von den Durchf{\"u}hrenden eine hohe Erfolgsquote garantiert. An den Universit{\"a}ten T{\"u}bingen und Freiburg wurde die Informatik I aus den gleichen Lehrmaterialien und unter {\"a}hnlichen Bedingungen durchgef{\"u}hrt, um das verwendete Konzept auf Robustheit zu {\"u}berpr{\"u}fen. Die Grundlage der Vorlesung bildet ein systematischer Ansatz zum Erlernen des Programmierens, der von der PLTGruppe in USA entwickelt worden ist. Hinzu kommen neue Ans{\"a}tze zur Betreuung, insbesondere das Betreute Programmieren, bei dem die Studierenden eine solide Basis f{\"u}r ihre Programmierf{\"a}higkeiten entwickeln. Der vorliegende Bericht beschreibt hierbei gesammelte Erfahrungen, erl{\"a}utert die Entwicklung der Unterrichtsmethodik und der Inhaltsauswahl im Vergleich zu vorangegangenen Vorlesungen und pr{\"a}sentiert Daten zum Erfolg der Vorlesung.}, language = {de} } @article{IshebabiBobda2009, author = {Ishebabi, Harold and Bobda, Christophe}, title = {Automated architecture synthesis for parallel programs on FPGA multiprocessor systems}, issn = {0141-9331}, doi = {10.1016/j.micpro.2008.08.009}, year = {2009}, abstract = {This paper presents a concept for automated architecture synthesis for adaptive multiprocessors on chip, in particular for Field-Programmable Gate-Array (FPGA) devices. Given a parallel program, the intent is to simultaneously allocate processor resources and the corresponding communication network, and at the same time, to map the parallel application to get an optimum application-specific architecture. This approach builds up on a previously proposed design platform that automates system integration and FPGA synthesis for such architectures. As a result, the overall concept offers an automated design approach from application mapping to system and FPGA configuration. The automated synthesis is based on combinatorial optimization. Automation is possible because a solvable Integer Linear Programming (ILP) model that captures all necessary design trade-off parameters of such systems has been found. Experimental results to study the feasibility of the automated synthesis indicate that problems with sizes that can be encountered in the embedded domain can be readily solved. Results obtained underscore the need for an automated synthesis for design space exploration.}, language = {en} } @article{HaiderScheffer2009, author = {Haider, Peter and Scheffer, Tobias}, title = {Bayesian clustering for email campaign detection}, isbn = {978-1-605-58516-1}, year = {2009}, language = {en} } @misc{LamprechtMargariaSteffen2009, author = {Lamprecht, Anna-Lena and Margaria, Tiziana and Steffen, Bernhard}, title = {Bio-jETI : a framework for semantics-based service composition}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-45066}, year = {2009}, abstract = {Background: The development of bioinformatics databases, algorithms, and tools throughout the last years has lead to a highly distributedworld of bioinformatics services. Without adequatemanagement and development support, in silico researchers are hardly able to exploit the potential of building complex, specialized analysis processes from these services. The Semantic Web aims at thoroughly equipping individual data and services with machine-processable meta-information, while workflow systems support the construction of service compositions. However, even in this combination, in silico researchers currently would have to deal manually with the service interfaces, the adequacy of the semantic annotations, type incompatibilities, and the consistency of service compositions. Results: In this paper, we demonstrate by means of two examples how Semantic Web technology together with an adequate domain modelling frees in silico researchers from dealing with interfaces, types, and inconsistencies. In Bio-jETI, bioinformatics services can be graphically combined to complex services without worrying about details of their interfaces or about type mismatches of the composition. These issues are taken care of at the semantic level by Bio-jETI's model checking and synthesis features. Whenever possible, they automatically resolve type mismatches in the considered service setting. Otherwise, they graphically indicate impossible/incorrect service combinations. In the latter case, the workflow developermay either modify his service composition using semantically similar services, or ask for help in developing the missing mediator that correctly bridges the detected type gap. Newly developed mediators should then be adequately annotated semantically, and added to the service library for later reuse in similar situations. Conclusion: We show the power of semantic annotations in an adequately modelled and semantically enabled domain setting. Using model checking and synthesis methods, users may orchestrate complex processes from a wealth of heterogeneous services without worrying about interfaces and (type) consistency. The success of this method strongly depends on a careful semantic annotation of the provided services and on its consequent exploitation for analysis, validation, and synthesis. We are convinced that these annotations will become standard, as they will become preconditions for the success and widespread use of (preferred) services in the Semantic Web}, language = {en} } @article{Schulte2009, author = {Schulte, Carsten}, title = {Biographisches Lernen in der Informatik}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {1}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29649}, pages = {47 -- 63}, year = {2009}, abstract = {Biographisches Lernen betont insbesondere die Rolle individueller biographischer Erfahrungen und deren Auswirkungen auf Selbstbild, Weltbild und Verhaltensmuster. Schlagwortartig kann diese Perspektive als Unterschied zwischen ‚Informatik lernen' und ‚Informatiker/in werden' beschrieben werden. Im Artikel wird die Perspektive des Biographischen Lernens an Beispielen aus der Informatik skizziert. Biographisches Lernen ist in der Informatik zun{\"a}chst aus rein pragmatischen Gr{\"u}nden bedeutsam. Der rasche Wandel der Informationstechnologien im Alltag ver{\"a}ndert Erfahrungshintergr{\"u}nde der Studierenden (bzw. Sch{\"u}lerinnen und Sch{\"u}ler). Dementsprechend ver{\"a}ndern sich Erwartungen, Interessen, Vorkenntnisse, generelle Einstellungen oder auch ganz banal die ‚IT-Ausstattung' der Lernenden.}, language = {de} } @article{MargariaSteffen2009, author = {Margaria, Tiziana and Steffen, Bernhard}, title = {Continuous model-driven engineering}, issn = {0018-9162}, year = {2009}, abstract = {Agility at the customer, user, and application level will prove key to aligning and linking business and IT}, language = {en} } @phdthesis{Decker2009, author = {Decker, Gero}, title = {Design and analysis of process choreographies}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-40761}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {With the rise of electronic integration between organizations, the need for a precise specification of interaction behavior increases. Information systems, replacing interaction previously carried out by humans via phone, faxes and emails, require a precise specification for handling all possible situations. Such interaction behavior is described in process choreographies. Choreographies enumerate the roles involved, the allowed interactions, the message contents and the behavioral dependencies between interactions. Choreographies serve as interaction contract and are the starting point for adapting existing business processes and systems or for implementing new software components. As a thorough analysis and comparison of choreography modeling languages is missing in the literature, this thesis introduces a requirements framework for choreography languages and uses it for comparing current choreography languages. Language proposals for overcoming the limitations are given for choreography modeling on the conceptual and on the technical level. Using an interconnection modeling style, behavioral dependencies are defined on a per-role basis and different roles are interconnected using message flow. This thesis reveals a number of modeling "anti-patterns" for interconnection modeling, motivating further investigations on choreography languages following the interaction modeling style. Here, interactions are seen as atomic building blocks and the behavioral dependencies between them are defined globally. Two novel language proposals are put forward for this modeling style which have already influenced industrial standardization initiatives. While avoiding many of the pitfalls of interconnection modeling, new anomalies can arise in interaction models. A choreography might not be realizable, i.e. there does not exist a set of interacting roles that collectively realize the specified behavior. This thesis investigates different dimensions of realizability.}, language = {en} } @article{BordihnHolzerKutrib2009, author = {Bordihn, Henning and Holzer, Markus and Kutrib, Martin}, title = {Determination of finite automata accepting subregular languages}, issn = {0304-3975}, doi = {10.1016/j.tcs.2009.05.019}, year = {2009}, abstract = {We investigate the descriptional complexity of the nondeterministic finite automaton (NFA) to the deterministic finite automaton (DFA) conversion problem, for automata accepting subregular languages such as combinational languages, definite languages and variants thereof, (strictly) locally testable languages, star-free languages, ordered languages, prefix-, suffix-, and infix-closed languages, and prefix-, Suffix-, and infix-free languages. Most of the bounds for the conversion problem are shown to be tight ill the exact number of states, that is, the number is sufficient and necessary in the worst case. Otherwise tight bounds in order of magnitude are shown.}, language = {en} } @book{Lehker2009, author = {Lehker, Christoph}, title = {Deutsch+ - flexibel, lernerzentriert, anwendungsorientiert : das Lernarrangement f{\"u}r Doktoranden : eLearning UP 2009 : Sonderveranstaltung 2009-11-25}, publisher = {Univ.-Bibl.}, address = {Potsdam}, year = {2009}, language = {de} } @book{MeinelSack2009, author = {Meinel, Christoph and Sack, Harald}, title = {Digitale Kommunikation : Vernetzen, Multimedia, Sicherheit}, series = {Media Press}, journal = {Media Press}, publisher = {Springer-Verlag Berlin Heidelberg}, address = {Berlin, Heidelberg}, isbn = {978-3-540-92922-2}, issn = {1439-3107}, doi = {10.1007/978-3-540-92923-9}, pages = {422 S.}, year = {2009}, language = {de} } @article{BickelBruecknerScheffer2009, author = {Bickel, Steffen and Br{\"u}ckner, Michael and Scheffer, Tobias}, title = {Discriminative learning under covariate shift}, issn = {1532-4435}, year = {2009}, abstract = {We address classification problems for which the training instances are governed by an input distribution that is allowed to differ arbitrarily from the test distribution-problems also referred to as classification under covariate shift. We derive a solution that is purely discriminative: neither training nor test distribution are modeled explicitly. The problem of learning under covariate shift can be written as an integrated optimization problem. Instantiating the general optimization problem leads to a kernel logistic regression and an exponential model classifier for covariate shift. The optimization problem is convex under certain conditions; our findings also clarify the relationship to the known kernel mean matching procedure. We report on experiments on problems of spam filtering, text classification, and landmine detection.}, language = {en} } @article{BickelBruecknerScheffer2009, author = {Bickel, Steffen and Brueckner, Michael and Scheffer, Tobias}, title = {Discriminative learning under covariate shift}, issn = {1532-4435}, year = {2009}, abstract = {We address classification problems for which the training instances are governed by an input distribution that is allowed to differ arbitrarily from the test distribution-problems also referred to as classification under covariate shift. We derive a solution that is purely discriminative: neither training nor test distribution are modeled explicitly. The problem of learning under covariate shift can be written as an integrated optimization problem. Instantiating the general optimization problem leads to a kernel logistic regression and an exponential model classifier for covariate shift. The optimization problem is convex under certain conditions; our findings also clarify the relationship to the known kernel mean matching procedure. We report on experiments on problems of spam filtering, text classification, and landmine detection.}, language = {en} } @article{DinesLiuSchulze2009, author = {Dines, Nicoleta and Liu, Xiaochun and Schulze, Bert-Wolfgang}, title = {Edge quantisation of elliptic operators}, series = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, journal = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, issn = {1437-739X}, doi = {10.1007/s00605-008-0058-y}, year = {2009}, abstract = {The ellipticity of operators on a manifold with edge is defined as the bijectivity of the components of a principal symbolic hierarchy sigma = (sigma(psi), sigma(boolean AND)), where the second component takes values in operators on the infinite model cone of the local wedges. In the general understanding of edge problems there are two basic aspects: Quantisation of edge-degenerate operators in weighted Sobolev spaces, and verifying the ellipticity of the principal edge symbol sigma(boolean AND) which includes the (in general not explicity known) number of additional conditions of trace and potential type on the edge. We focus here on these questions and give explicit answers for a wide class of elliptic operators that are connected with the ellipticity of edge boundary value problems and reductions to the boundary. In particular, we study the edge quantisation and ellipticity for Dirichlet-Neumann operators with respect to interfaces of some codimension on a boundary. We show analogues of the Agranovich-Dynin formula for edge boundary value problems.}, language = {en} } @article{BenderSteinert2009, author = {Bender, Katrin and Steinert, Markus}, title = {Ein handlungsorientiertes, didaktisches Training f{\"u}r Tutoren im Bachelorstudium der Informatik}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {1}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29690}, pages = {119 -- 130}, year = {2009}, abstract = {Die didaktisch-p{\"a}dagogische Ausbildung studentischer Tutoren f{\"u}r den Einsatz im Bachelorstudium der Informatik ist Gegenstand dieser Arbeit. Um die theoretischen Inhalte aus Sozial- und Lernpsychologie handlungsorientiert und effizient zu vermitteln, wird das Training als Lehrform gew{\"a}hlt. Die in einer Tutor{\"u}bung zentrale Methode der Gruppenarbeit wird dabei explizit und implizit vermittelt. Erste praktische Erfahrungen mit ihrer zuk{\"u}nftigen Rolle gewinnen die Tutoren in Rollenspielen, wobei sowohl Standardsituationen als auch fachspezifisch und p{\"a}dagogisch problematische Situationen simuliert werden. W{\"a}hrend die Vermittlung der genannten Inhalte und die Rollenspiele im Rahmen einer Blockveranstaltung vor Beginn des Semesters durchgef{\"u}hrt werden, finden w{\"a}hrend des Semesters Hospitationen statt, in der die F{\"a}higkeiten der Tutoren anhand eines standardisierten Bewertungsbogens beurteilt werden.}, language = {de} }