@inproceedings{247, abstract = {{Multi-rooted trees are becoming the norm for modern data-center networks. In these networks, scalable flow routing is challenging owing to vast number of flows. Current approaches either employ a central controller that can have scalability issues or a scalable decentralized algorithm only considering local information. In this paper we present a new decentralized approach to least-congested path routing in software-defined data center networks that has neither of these issues: By duplicating the initial (or SYN) packet of a flow and estimating the data rate of multiple flows in parallel, we exploit TCP’s habit to fill buffers to find the least congested path. We show that our algorithm significantly improves flow completion time without the need for a central controller or specialized hardware.}}, author = {{Schwabe, Arne and Karl, Holger}}, booktitle = {{Proceedings of the 4th European Workshop on Software Defined Networks (EWSDN 2015)}}, pages = {{37--42}}, title = {{{SynRace: Decentralized Load-Adaptive Multi-path Routing without Collecting Statistics}}}, doi = {{10.1109/EWSDN.2015.58}}, year = {{2015}}, } @misc{261, author = {{Eisenhofer, Thorsten}}, publisher = {{Universität Paderborn}}, title = {{{Protokolle zur authentifizierten Schüsselvereinbarung}}}, year = {{2015}}, } @inproceedings{262, abstract = {{Programs from Proofs" is a generic method which generates new programs out of correctness proofs of given programs. The technique ensures that the new and given program are behaviorally equivalent and that the new program is easily verifiable, thus serving as an alternative to proof-carrying code concepts. So far, this generic method has one instantiation that verifies type-state properties of programs. In this paper, we present a whole range of new instantiations, all based on data ow analyses. More precisely, we show how an imprecise but fast data ow analysis can be enhanced with a predicate analysis as to yield a precise but expensive analysis. Out of the safety proofs of this analysis, we generate new programs, again behaviorally equivalent to the given ones, which are easily verifiable" in the sense that now the data ow analysis alone can yield precise results. An experimental evaluation practically supports our claim of easy verification.}}, author = {{Jakobs, Marie-Christine and Wehrheim, Heike}}, booktitle = {{Proceedings of the 30th Annual ACM Symposium on Applied Computing}}, pages = {{1729--1736}}, title = {{{Programs from Proofs of Predicated Dataflow Analyses}}}, doi = {{10.1145/2695664.2695690}}, year = {{2015}}, } @phdthesis{264, author = {{Wette, Philip}}, publisher = {{Universität Paderborn}}, title = {{{Optimizing Software-Defined Networks using Application-Layer Knowledge}}}, year = {{2015}}, } @book{26446, author = {{Pongratz, Hans and Keil, Reinhard}}, publisher = {{Koellen Druck + Verlag GmbH}}, title = {{{DeLFI 2015 - The 13th e-Learning Conference on Computer Science of the E-Learning Section of the Society for Computer Science eV}}}, year = {{2015}}, } @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}}, }