@inproceedings{26449, author = {{Winkelnkemper, Felix and Oberhoff, Andreas}}, editor = {{wedge, Reinhard and Selke, Harald}}, pages = {{103--117}}, publisher = {{Publication series of the Heinz Nixdorf Institute, Paderborn}}, title = {{{WebArena - R {\ "a} spacious structures for {\" u} r the learning locations of the future}}}, volume = {{330}}, year = {{2015}}, } @book{26531, editor = {{Keil, Reinhard and Selke, Harald}}, publisher = {{publishing series of the Heinz Nixdorf Institute, Paderborn}}, title = {{{20 years of learning with the World Wide Web - technology and education in dialogue}}}, volume = {{330}}, year = {{2015}}, } @inproceedings{26532, author = {{Keil, Reinhard and Selke, Harald}}, editor = {{Keil, Reinhard and Selke, Harald}}, pages = {{1--7}}, publisher = {{Publishing series of the Heinz Nixdorf Institute, Paderborn}}, title = {{{Learn with, through and {\ "about the WWW}}}, volume = {{330}}, year = {{2015}}, } @inproceedings{26533, author = {{Keil, Reinhard and Selke, Harald}}, editor = {{Keil, Reinhard and Selke, Harald}}, pages = {{39--53}}, publisher = {{publishing series of the Heinz Nixdorf Institute, Paderborn}}, title = {{{Virtual knowledge {\ "a} ume - From the presentation of content to virtual learning {\" a} tten}}}, volume = {{330}}, year = {{2015}}, } @phdthesis{26534, author = {{Klompmaker, Florian}}, publisher = {{Universitaetsbibliothek Paderborn}}, title = {{{Development of a structured process of interaction design for {\ "u} r nat {\" u} local user interfaces}}}, year = {{2015}}, } @inproceedings{26536, abstract = {{Patterns serve to codify design knowledge. By embedding them in a hypothesis-driven design, it is possible to develop them further into sample languages. For this it is necessary to resolve the underlying conflicts in the form of design hypotheses and to validate them empirically in order to enable further use and generalization. In this article, an experiment is presented that describes this procedure and demonstrates the interplay between theory formation and codification of design knowledge using two examples. }}, author = {{Schild, Christian and Petrausch, Vanessa}}, booktitle = {{Human and Computer 2015 - Proceedings}}, pages = {{173--182}}, publisher = {{De Gruyter Oldenbourg}}, title = {{{Empirical validation of design patterns}}}, year = {{2015}}, } @inproceedings{266, abstract = {{Many markets have seen a shift from the idea of buying and moved to leasing instead. Arguably, the latter has been the major catalyst for their success. Ten years ago, research realized this shift and initiated the study of "online leasing problems" by introducing leasing to online optimization problems. Resources required to provide a service in an "online leasing problem" are no more bought but leased for different durations. In this paper, we provide an overview of results that contribute to the understanding of "online resource leasing problems". }}, author = {{Markarian, Christine and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 2015 ACM Symposium on Principles of Distributed Computing (PODC)}}, pages = {{343--344}}, title = {{{Online Resource Leasing}}}, doi = {{10.1145/2767386.2767454}}, year = {{2015}}, } @phdthesis{267, author = {{Markarian, Christine}}, publisher = {{Universität Paderborn}}, title = {{{Online Resource Leasing}}}, year = {{2015}}, } @inproceedings{269, abstract = {{Proof-carrying hardware is an approach that has recently been proposed for the efficient verification of reconfigurable modules. We present an application of proof-carrying hardware to guarantee the correct functionality of dynamically reconfigured image processing modules. Our prototype comprises a reconfigurable-system-on-chip with an embedded virtual FPGA fabric. This setup allows us to leverage open source FPGA synthesis and backend tools to produce FPGA configuration bitstreams with an open format and, thus, to demonstrate and experimentally evaluate proof-carrying hardware at the bitstream level.}}, author = {{Wiersema, Tobias and Wu, Sen and Platzner, Marco}}, booktitle = {{Proceedings of the International Symposium in Reconfigurable Computing (ARC)}}, pages = {{365----372}}, title = {{{On-The-Fly Verification of Reconfigurable Image Processing Modules based on a Proof-Carrying Hardware Approach}}}, doi = {{10.1007/978-3-319-16214-0_32}}, year = {{2015}}, } @article{320, abstract = {{We consider structural and algorithmic questions related to the Nash dynamics of weighted congestion games. In weighted congestion games with linear latency functions, the existence of pure Nash equilibria is guaranteed by a potential function argument. Unfortunately, this proof of existence is inefficient and computing pure Nash equilibria in such games is a PLS-hard problem even when all players have unit weights. The situation gets worse when superlinear (e.g., quadratic) latency functions come into play; in this case, the Nash dynamics of the game may contain cycles and pure Nash equilibria may not even exist. Given these obstacles, we consider approximate pure Nash equilibria as alternative solution concepts. A ρ--approximate pure Nash equilibrium is a state of a (weighted congestion) game from which no player has any incentive to deviate in order to improve her cost by a multiplicative factor higher than ρ. Do such equilibria exist for small values of ρ? And if so, can we compute them efficiently?We provide positive answers to both questions for weighted congestion games with polynomial latency functions by exploiting an “approximation” of such games by a new class of potential games that we call Ψ-games. This allows us to show that these games have d!-approximate pure Nash equilibria, where d is the maximum degree of the latency functions. Our main technical contribution is an efficient algorithm for computing O(1)-approximate pure Nash equilibria when d is a constant. For games with linear latency functions, the approximation guarantee is 3+√5/2 + Oγ for arbitrarily small γ > 0; for latency functions with maximum degree d≥ 2, it is d2d+o(d). The running time is polynomial in the number of bits in the representation of the game and 1/γ. As a byproduct of our techniques, we also show the following interesting structural statement for weighted congestion games with polynomial latency functions of maximum degree d ≥ 2: polynomially-long sequences of best-response moves from any initial state to a dO(d2)-approximate pure Nash equilibrium exist and can be efficiently identified in such games as long as d is a constant.To the best of our knowledge, these are the first positive algorithmic results for approximate pure Nash equilibria in weighted congestion games. Our techniques significantly extend our recent work on unweighted congestion games through the use of Ψ-games. The concept of approximating nonpotential games by potential ones is interesting in itself and might have further applications.}}, author = {{Caragiannis, Ioannis and Fanelli, Angelo and Gravin, Nick and Skopalik, Alexander}}, journal = {{Transactions on Economics and Computation}}, number = {{1}}, publisher = {{ACM}}, title = {{{Approximate Pure Nash Equilibria in Weighted Congestion Games: Existence, Efficient Computation, and Structure}}}, doi = {{10.1145/2614687}}, volume = {{3}}, year = {{2015}}, } @misc{321, author = {{Eidens, Fabian}}, publisher = {{Universität Paderborn}}, title = {{{Anonymous credential system based on q-Strong Diffie-Hellman Assumption}}}, year = {{2015}}, } @inproceedings{322, abstract = {{Reputation systems are used to compute and publish reputation scores for services or products. We consider reputation systems where users are allowed to rate products that they purchased previously. To obtain trustworthy reputations, they are allowed to rate these products only once. As long as users rate products once, they stay anonymous. Everybody is able to detect users deviating from the rate-products-only-once policy and the anonymity of such dishonest users can be revoked by a system manager. In this paper we present formal models for such reputation systems and their security. Based on group signatures presented by Boneh, Boyen, and Shacham we design an efficient reputation system that meets all our requirements.}}, author = {{Blömer, Johannes and Juhnke, Jakob and Kolb, Christina}}, booktitle = {{Proceedings of the 18th International Conference on Financial Cryptography and Data Security (FC)}}, pages = {{478----488}}, title = {{{Anonymous and Publicly Linkable Reputation Systems}}}, doi = {{10.1007/978-3-662-47854-7_29}}, year = {{2015}}, } @article{323, abstract = {{On-the-fly composition of service-based software solutions is still a challenging task. Even more challenges emerge when facing automatic service composition in markets of composed services for end users. In this paper, we focus on the functional discrepancy between “what a user wants” specified in terms of a request and “what a user gets” when executing a composed service. To meet the challenge of functional discrepancy, we propose the combination of existing symbolic composition approaches with machine learning techniques. We developed a learning recommendation system that expands the capabilities of existing composition algorithms to facilitate adaptivity and consequently reduces functional discrepancy. As a representative of symbolic techniques, an Artificial Intelligence planning based approach produces solutions that are correct with respect to formal specifications. Our learning recommendation system supports the symbolic approach in decision-making. Reinforcement Learning techniques enable the recommendation system to adjust its recommendation strategy over time based on user ratings. We implemented the proposed functionality in terms of a prototypical composition framework. Preliminary results from experiments conducted in the image processing domain illustrate the benefit of combining both complementary techniques.}}, author = {{Jungmann, Alexander and Mohr, Felix}}, journal = {{Journal of Internet Services and Applications}}, number = {{1}}, pages = {{1--18}}, publisher = {{Springer}}, title = {{{An approach towards adaptive service composition in markets of composed services}}}, doi = {{10.1186/s13174-015-0022-8}}, year = {{2015}}, } @inproceedings{324, abstract = {{Services are self-contained software components that can beused platform independent and that aim at maximizing software reuse. Abasic concern in service oriented architectures is to measure the reusabilityof services. One of the most important qualities is the functionalreusability, which indicates how relevant the task is that a service solves.Current metrics for functional reusability of software, however, have verylittle explanatory power and do not accomplish this goal.This paper presents a new approach to estimate the functional reusabilityof services based on their relevance. To this end, it denes the degreeto which a service enables the execution of other services as its contri-bution. Based on the contribution, relevance of services is dened as anestimation for their functional reusability. Explanatory power is obtainedby normalizing relevance values with a reference service. The applicationof the metric to a service test set conrms its supposed capabilities.}}, author = {{Mohr, Felix}}, booktitle = {{Proceedings of the 14th International Conference on Software Reuse (ICSR)}}, pages = {{298----313}}, title = {{{A Metric for Functional Reusability of Services}}}, doi = {{10.1007/978-3-319-14130-5_21}}, year = {{2015}}, } @misc{325, author = {{Löken, Nils}}, publisher = {{Universität Paderborn}}, title = {{{A Group Signature Scheme with Distributed Group Management - An Application of Threshold Encryption}}}, year = {{2015}}, } @misc{326, author = {{Heihoff, Frederic}}, publisher = {{Universität Paderborn}}, title = {{{A group signature scheme based on the LSRW assumption}}}, year = {{2015}}, } @article{327, abstract = {{We consider the problem of resource discovery in distributed systems. In particular we give an algorithm, such that each node in a network discovers the address of any other node in the network. We model the knowledge of the nodes as a virtual overlay network given by a directed graph such that complete knowledge of all nodes corresponds to a complete graph in the overlay network. Although there are several solutions for resource discovery, our solution is the first that achieves worst-case optimal work for each node, i.e. the number of addresses (O(n)O(n)) or bits (O(nlog⁡n)O(nlog⁡n)) a node receives or sends coincides with the lower bound, while ensuring only a linear runtime (O(n)O(n)) on the number of rounds.}}, author = {{Kniesburges, Sebastian and Koutsopoulos, Andreas and Scheideler, Christian}}, journal = {{Theoretical Computer Science}}, pages = {{67--79}}, publisher = {{Elsevier}}, title = {{{A deterministic worst-case message complexity optimal solution for resource discovery}}}, doi = {{10.1016/j.tcs.2014.11.027}}, year = {{2015}}, } @article{3343, abstract = {{In this paper we consider an extended variant of query learning where the hidden concept is embedded in some Boolean circuit. This additional processing layer modifies query arguments and answers by fixed transformation functions which are known to the learner. For this scenario, we provide a characterization of the solution space and an ordering on it. We give a compact representation of the minimal and maximal solutions as quantified Boolean formulas and we adapt the original algorithms for exact learning of specific classes of propositional formulas.}}, author = {{Bubeck, Uwe and Kleine Büning, Hans}}, issn = {{0004-3702}}, journal = {{Artificial Intelligence}}, keywords = {{Query learning, Propositional logic}}, pages = {{246 -- 257}}, publisher = {{Elsevier}}, title = {{{Learning Boolean Specifications}}}, doi = {{10.1016/j.artint.2015.09.003}}, year = {{2015}}, } @misc{3364, author = {{Knorr, Christoph}}, publisher = {{Universität Paderborn}}, title = {{{Evaluation von Bildverarbeitungsalgorithmen in heterogenen Rechenknoten}}}, year = {{2015}}, } @inproceedings{3815, author = {{Wachsmuth, Henning and Kiesel, Johannes and Stein, Benno}}, booktitle = {{Proceedings of the 2015 Conference on Empirical Methods in Natural Language Processing}}, editor = {{Tsujii, Junichi and Hajic, Jan}}, isbn = {{978-3-319-25740-2}}, pages = {{601--611}}, title = {{{Sentiment Flow - A General Model of Web Review Argumentation}}}, doi = {{10.18653/v1/D15-1072}}, year = {{2015}}, }