@inproceedings{382, abstract = {{This paper explores how cloud provider competition influences instance pricing in an IaaS (Infrastructure-as-a-Service) market. When reserved instance pricing includes an on-demand price component in addition to a reservation fee (two-part tariffs), different providers might offer different price combinations, where the client’s choice depends on its load profile. We investigate a duopoly of providers and analyze stable market prices in two-part tariffs. Further, we study offers that allow a specified amount of included usage (three-part tariffs). Neither two-part nor three-part tariffs produce an equilibrium market outcome other than a service pricing that equals production cost, i.e., complex price structures do not significantly affect the results from ordinary Bertrand competition.}}, author = {{Künsemöller, Jörn and Brangewitz, Sonja and Karl, Holger and Haake, Claus-Jochen}}, booktitle = {{Proceedings of the 2014 IEEE International Conference on Services Computing (SCC)}}, pages = {{203--210}}, title = {{{Provider Competition in Infrastructure-as-a-Service}}}, doi = {{10.1109/SCC.2014.35}}, year = {{2014}}, } @inproceedings{383, abstract = {{Proof-carrying code approaches aim at safe execution of untrusted code by having the code producer attach a safety proof to the code which the code consumer only has to validate. Depending on the type of safety property, proofs can however become quite large and their validation - though faster than their construction - still time consuming. In this paper we introduce a new concept for safe execution of untrusted code. It keeps the idea of putting the time consuming part of proving on the side of the code producer, however, attaches no proofs to code anymore but instead uses the proof to transform the program into an equivalent but more efficiently verifiable program. Code consumers thus still do proving themselves, however, on a computationally inexpensive level only. Experimental results show that the proof effort can be reduced by several orders of magnitude, both with respect to time and space.}}, author = {{Wonisch, Daniel and Schremmer, Alexander and Wehrheim, Heike}}, booktitle = {{Proceedings of the Software Engineering Conference (SE)}}, pages = {{67--68}}, title = {{{Programs from Proofs -- Approach and Applications}}}, year = {{2014}}, } @inproceedings{384, abstract = {{Reputation systems provide reputation values of rated parties to users. These reputation values, typically aggregations of individual user ratings, shall be reliable, i.e. should enable a realistic assessment of the probability that the rated party behaves as expected in a transaction. In order for the reputation values to stay reliable and, thus, for the reputation system to provide a benefit, the system needs to be resistant against manipulations by users, the rated parties trying to improve their reputation values, and even against competitors trying to worsen a reputation value. At the same time, a reputation system shall provide privacy protection for users: rated parties shall not be able to learn who provided a certain rating. Otherwise users might not take part in the system as they fear bad feedback in revenge for bad ratings, or users do not want to be connected to certain transactions based on their provided ratings. In this paper we come up with a solution that provides both, reliability of reputation values on the one hand, and privacy protection for users on the other hand. In contrast to related work, our solution only makes use of a single reputation provider that needs to be trusted (to a certain extent) and does not require any bulletin boards to be present in the system. We make use of the Paillier cryptosystem to provide an aggregation of individual user ratings in a way that no party can learn which user provided a certain rating.}}, author = {{Petrlic, Ronald and Lutters, Sascha and Sorge, Christoph}}, booktitle = {{Proceedings of the 29th Symposium On Applied Computing (SAC)}}, pages = {{1712--1718}}, title = {{{Privacy-Preserving Reputation Management}}}, doi = {{10.1145/2554850.2554881}}, year = {{2014}}, } @phdthesis{385, author = {{Petrlic, Ronald}}, publisher = {{Universität Paderborn}}, title = {{{Privacy-Preserving Multiparty Digital Rights Management}}}, year = {{2014}}, } @inproceedings{386, abstract = {{We present a privacy-preserving multiparty DRM scheme that does not need a trusted third party. Users anonymously buy content from content providers and anonymously execute it at content execution centers. The executions are unlinkable to each other. The license check is performed as part of the used ciphertext-policy attribute-based encryption (CP-ABE) and, thus, access control is cryptographically enforced. The problem of authorization proof towards the key center in an ABE scheme is solved by a combination with anonymous payments.}}, author = {{Petrlic, Ronald and Sorge, Christoph}}, booktitle = {{Proceedings of the Sixth IFIP International Conference on New Technologies, Mobility and Security (NTMS)}}, pages = {{1--5}}, title = {{{Privacy-Preserving Digital Rights Management based on Attribute-based Encryption}}}, doi = {{10.1109/NTMS.2014.6814044}}, year = {{2014}}, } @article{387, abstract = {{This article studies the design of medium access control (MAC) protocols for wireless networks that are provably robust against arbitrary and unpredictable disruptions (e.g., due to unintentional external interference from co-existing networks or due to jamming). We consider a wireless network consisting of a set of n honest and reliable nodes within transmission (and interference) range of each other, and we model the external disruptions with a powerful adaptive adversary. This adversary may know the protocol and its entire history and can use this knowledge to jam the wireless channel at will at any time. It is allowed to jam a (1 − )-fraction of the timesteps, for an arbitrary constant > 0 unknown to the nodes. The nodes cannot distinguish between the adversarial jamming or a collision of two or more messages that are sent at the same time. We demonstrate, for the first time, that there is a local-control MAC protocol requiring only very limited knowledge about the adversary and the network that achieves a constant (asymptotically optimal) throughput for the nonjammed time periods under any of the aforementioned adversarial strategies. The derived principles are also useful to build robust applications on top of the MAC layer, and we present an exemplary study for leader election, one of the most fundamental tasks in distributed computing.}}, author = {{Awerbuch, Baruch and Richa, Andrea W. and Scheideler, Christian and Schmid, Stefan and Zhang, Jin}}, journal = {{Transactions on Algorithms}}, number = {{4}}, publisher = {{ACM}}, title = {{{Principles of Robust Medium Access and an Application to Leader Election}}}, doi = {{10.1145/2635818}}, year = {{2014}}, } @techreport{389, abstract = {{This article presents a new approach for representing and processing abstract optimization models. Confronted with model and data integration tasks for distributed Decision Support Systems which are especially composed out of software services, we describe model constituents such as constraints both structurally and semantically. Within our approach, typed model constituents can be integrated into complete models and the instantiation of model constituents itself with data and data models can be wrapped into semantic software services. Besides others, this supports the automated generation of adaptors and the search for and composition of services. The basic idea of our approach is to represent the optimization models as instance knowledge of different ontologies for both optimization and application domains. By separating the model expression structure from the goal and constraint conceptualizations predefined modeling constructs can be reused, where we do not only separate the model structure from data, but can also abstract the structure from a specific data model. We present an XML and ontology-query based approach for this separation and demonstrate the resulting flexible model integration procedure out of reusable goal and constraint types on a network flow problem.}}, author = {{Stapel, Florian and Suhl, Lena}}, publisher = {{Universität Paderborn}}, title = {{{Ontology-based Representation of Optimization Models}}}, year = {{2014}}, } @article{390, abstract = {{In software markets of the future, customer-specific software will be developed on demand based on distributed software and hardware services. Based on a customer-specific request, available service offers have to be discovered and composed into sophisticated IT services that fulfill the customer's request.A prerequisite of this vision are rich service descriptions, which comprise structural as well as behavioral aspects of the services, otherwise an accurate service discovery and composition is not possible. However, automatic matching of service requests and offers specified in rich service descriptions for the purpose of service discovery is a complex task, due to the multifaceted heterogeneity of the service partners. This heterogeneity includes the use of different specification languages, different underlying ontologies, or different levels of granularity in the specification itself.In this article, we present a comprehensive approach for service discovery and composition, which overcomes the underlying heterogeneity of the service partners. Based on a realistic case study of our industrial partner from the e-tourism domain, we first introduce an automatic matching mechanism for service requests and offers specified in a rich service description language. In addition, we propose an automatic service composition approach, which determines possible service compositions by composing the service protocols through a composition strategy based on labeled transition systems. }}, author = {{Huma, Zille and Gerth, Christian and Engels, Gregor}}, journal = {{Computer Science - Research and Development}}, number = {{3-4}}, pages = {{333--361}}, publisher = {{Springer}}, title = {{{On-the-Fly Computing: Automatic Service Discovery and Composition in Heterogeneous Domains}}}, doi = {{10.1007/s00450-014-0254-z}}, year = {{2014}}, } @misc{391, author = {{Feldkord, Björn}}, publisher = {{Universität Paderborn}}, title = {{{On Variants of the Page Migration Problem}}}, year = {{2014}}, } @misc{18001, author = {{Luo, Linghui}}, publisher = {{Universität Paderborn}}, title = {{{Ein selbst-stabilisierender Algorithmus für das Finite Sleep Problem in Skip+ Graphen}}}, year = {{2014}}, } @inproceedings{441, abstract = {{Das Future Internet soll den Anforderungen heutiger und zuk{\"u}nftiger daten-intensiver Internet-Anwendungen besser gerecht werden als dies heute der Fall ist. Seit einigen Jahren wird an unterschiedlichen Verfahren geforscht, die das „Future Internet“ erm{\"o}glichen sollen – diese Ans{\"a}tze gehen weit {\"u}ber die Ziele von IPv6 hinaus. In diesem Beitrag stellen wir einige Kernpunkte der Future-Internet-Initiativen vor und identifizieren Gemeinsamkeiten der unterschiedlichen Konzepte. Wir beleuchten die Konsequenzen aus datenschutzrechtlicher Sicht und geben einen {\"U}berblick {\"u}ber Ans{\"a}tze, die die identifizierten Datenschutz-Probleme durch technische Maßnahmen bis zu einem gewissen Grad verhindern.}}, author = {{Sorge, Christoph and Petrlic, Ronald}}, booktitle = {{Tagungsband des 17. Internationalen Rechtsinformatik Symposions}}, title = {{{Datenschutz im Future Internet: rechtliche Aspekte und technische Maßnahmen}}}, year = {{2014}}, } @unpublished{442, abstract = {{We present a new transformation of chosen-plaintext secure predicate encryption schemes with public index into chosen-ciphertext secure schemes. Our construction requires only a universal one-way hash function and is selectively secure in the standard model. The transformation is not generic but can be applied to various existing schemes constructed from bilinear groups. Using common structural properties of these schemes we provide an efficient and simple transformation without overhead in form of one-time signatures or message authentication codes as required in the known generic transformations.}}, author = {{Blömer, Johannes and Liske, Gennadij}}, publisher = {{Universität Paderborn}}, title = {{{Constructing CCA-secure predicate encapsulation schemes from CPA-secure schemes and universal one-way hash functions}}}, year = {{2014}}, } @techreport{443, abstract = {{The objective of this paper is to analyze the formation of group structures where individuals are allowed to engage in several groups at the same time. These structures are interpreted here as social networks. Each of the groups is supposed to have specific rules or constitutions governing which members may join or leave it. A social network is then considered to be stable if none of the groups is altered any more. Given this framework, we not only analyze which influence the constitutions have on network formation but we also provide requirements under which stable networks are induced for sure. Furthermore, by embedding many-to-many matchings into our setting, we apply our model to job markets with labor unions. To some extent the unions may provide job guarantees and, therefore, have influence on the stability of the job market.}}, author = {{Mauleon, Ana and Röhl, Nils and Vannetelbosch, Vincent}}, publisher = {{Universität Paderborn}}, title = {{{Constitutions and Social Networks}}}, year = {{2014}}, } @article{444, abstract = {{BackgroundMedical nonpersistence is a worldwide problem of striking magnitude. Although many fields of studies including epidemiology, sociology, and psychology try to identify determinants for medical nonpersistence, comprehensive research to explain medical nonpersistence from an economics perspective is rather scarce.ObjectivesThe aim of the study was to develop a conceptual framework that augments standard economic choice theory with psychological concepts of behavioral economics to understand how patients’ preferences for discontinuing with therapy arise over the course of the medical treatment. The availability of such a framework allows the targeted design of mechanisms for intervention strategies.MethodsOur conceptual framework models the patient as an active economic agent who evaluates the benefits and costs for continuing with therapy. We argue that a combination of loss aversion and mental accounting operations explains why patients discontinue with therapy at a specific point in time. We designed a randomized laboratory economic experiment with a student subject pool to investigate the behavioral predictions.ResultsSubjects continue with therapy as long as experienced utility losses have to be compensated. As soon as previous losses are evened out, subjects perceive the marginal benefit of persistence lower than in the beginning of the treatment. Consequently, subjects start to discontinue with therapy.ConclusionsOur results highlight that concepts of behavioral economics capture the dynamic structure of medical nonpersistence better than does standard economic choice theory. We recommend that behavioral economics should be a mandatory part of the development of possible intervention strategies aimed at improving patients’ compliance and persistence behavior.}}, author = {{Mir Djawadi, Behnud and Fahr, Rene and Turk, Florian}}, journal = {{Value in Health}}, number = {{8}}, pages = {{814--822}}, publisher = {{Elsevier}}, title = {{{Conceptual Model and Economic Experiments to Explain Nonpersistence and Enable Mechanism Designs Fosterin Behavioral Change}}}, doi = {{10.1016/j.jval.2014.08.2669}}, year = {{2014}}, } @article{445, abstract = {{We consider the inner core as a solution concept for cooperative games with non-transferable utility (NTU) and its relationship to payoffs of competitive equilibria of markets that are induced by NTU games. An NTU game is an NTU market game if there exists a market such that the set of utility allocations a coalition can achieve in the market coincides with the set of utility allocations the coalition can achieve in the game. In this paper, we introduce a new construction of a market based on a closed subset of the inner core which satisfies a strict positive separability. We show that the constructed market represents the NTU game and, further, has the given closed set as the set of payoff vectors of competitive equilibria. It turns out that this market is not uniquely determined, and thus, we obtain a class of markets. Our results generalize those relating to competitive outcomes of NTU market games in the literature.}}, author = {{Brangewitz, Sonja and Gamp, Jan-Philip}}, journal = {{Economic Theory}}, number = {{3}}, pages = {{529--554}}, publisher = {{Springer}}, title = {{{Competitive outcomes and the inner core of NTU market games}}}, doi = {{10.1007/s00199-014-0846-7}}, year = {{2014}}, } @inproceedings{446, abstract = {{This paper considers the problem of how to efficiently share a wireless medium which is subject to harsh external interference or even jamming. While this problem has already been studied intensively for simplistic single-hop or unit disk graph models, we make a leap forward and study MAC protocols for the SINR interference model (a.k.a. the physical model). We make two contributions. First, we introduce a new adversarial SINR model which captures a wide range of interference phenomena. Concretely, we consider a powerful, adaptive adversary which can jam nodes at arbitrary times and which is only limited by some energy budget. The second contribution of this paper is a distributed MAC protocol which provably achieves a constant competitive throughput in this environment: we show that, with high probability, the protocol ensures that a constant fraction of the non-blocked time periods is used for successful transmissions.}}, author = {{Ogierman, Adrian and Richa, Andrea W. and Scheideler, Christian and Schmid, Stefan and Zhang, Jin}}, booktitle = {{Proceedings of the 33rd Annual IEEE International Conference on Computer Communications (INFOCOM)}}, pages = {{2751----2759}}, title = {{{Competitive MAC under adversarial SINR}}}, doi = {{10.1109/INFOCOM.2014.6848224}}, year = {{2014}}, } @inproceedings{447, abstract = {{Automatic service composition is still a challengingtask. It is even more challenging when dealing witha dynamic market of services for end users. New servicesmay enter the market while other services are completelyremoved. Furthermore, end users are typically no experts in thedomain in which they formulate a request. As a consequence,ambiguous user requests will inevitably emerge and have tobe taken into account. To meet these challenges, we proposea new approach that combines automatic service compositionwith adaptive service recommendation. A best first backwardsearch algorithm produces solutions that are functional correctwith respect to user requests. An adaptive recommendationsystem supports the search algorithm in decision-making.Reinforcement Learning techniques enable the system to adjustits recommendation strategy over time based on user ratings.The integrated approach is described on a conceptional leveland demonstrated by means of an illustrative example fromthe image processing domain.}}, author = {{Jungmann, Alexander and Mohr, Felix and Kleinjohann, Bernd}}, booktitle = {{Proceedings of the 10th World Congress on Services (SERVICES)}}, pages = {{346--353}}, title = {{{Combining Automatic Service Composition with Adaptive Service Recommendation for Dynamic Markets of Services}}}, doi = {{10.1109/SERVICES.2014.68}}, year = {{2014}}, } @misc{448, author = {{Gao, Yuan}}, publisher = {{Universität Paderborn}}, title = {{{Combination of Service Matching Steps in Consideration of Efficiency and Fuzziness}}}, year = {{2014}}, } @inproceedings{449, abstract = {{Cloud computing resulted in a continuously growing number of provided software services to be used by consumers. Brokers discover services that fit best to consumers' requirements by matching Qualityof-Service (QoS) properties. In order to negotiate Service-Level Agreements (SLAs), a provider has to determine the provided QoS based on QoS analyses. However, the risk for the provider to violate the SLA is high as the service's actual quality can deviate from the specified QoS due to uncertainties that occur during the provider's quality analysis. In this paper, we discuss current software engineering paradigms like cloud computing and service-oriented computing with respect to the amount of uncertainty they induce into service matching and SLA negotiations. As a result, we explain, why cloud computing reduces such uncertainties.}}, author = {{Becker, Matthias and Platenius, Marie Christin and Becker, Steffen}}, booktitle = {{Proceedings of the 2nd International Workshop on Cloud Service Brokerage (CSB)}}, pages = {{153--159}}, title = {{{Cloud Computing Reduces Uncertainties in Quality-of-Service Matching!}}}, doi = {{10.1007/978-3-319-14886-1_15}}, year = {{2014}}, } @inproceedings{450, abstract = {{Configurable program analysis (CPA) is a generic concept for the formalization of different software analysis techniques in a single framework. With the tool CPAchecker, this framework allows for an easy configuration and subsequent automatic execution of analysis procedures ranging from data-flow analysis to model checking. The focus of the tool CPAchecker is thus on analysis. In this paper, we study configurability from the point of view of software certification. Certification aims at providing (via a prior analysis) a certificate of correctness for a program which is (a) tamper-proof and (b) more efficient to check for validity than a full analysis. Here, we will show how, given an analysis instance of a CPA, to construct a corresponding sound certification instance, thereby arriving at configurable program certification. We report on experiments with certification based on different analysis techniques, and in particular explain which characteristics of an underlying analysis allow us to design an efficient (in the above (b) sense) certification procedure. }}, author = {{Jakobs, Marie-Christine and Wehrheim, Heike}}, booktitle = {{Proceedings of the 21st International Symposium on Model Checking of Software (SPIN)}}, pages = {{30--39}}, title = {{{Certification for Configurable Program Analysis}}}, doi = {{10.1145/2632362.2632372}}, year = {{2014}}, }