@inproceedings{2681, author = {{Görzen, Thomas and Laux, Florian}}, booktitle = {{Tagungsband Multikonferenz Wirtschaftsinformatik 2018 (MKWI)}}, location = {{Lüneburg}}, title = {{{Extracting the Wisdom from the Crowd: A Comparison of Approaches to Aggregating Collective Intelligence}}}, year = {{2018}}, } @article{2685, author = {{Blömer, Johannes and Kohn, Kathlén}}, issn = {{2470-6566}}, journal = {{SIAM Journal on Applied Algebra and Geometry.}}, number = {{2}}, pages = {{314--338}}, title = {{{Voronoi Cells of Lattices with Respect to Arbitrary Norms}}}, doi = {{10.1137/17M1132045}}, volume = {{2}}, year = {{2018}}, } @inproceedings{3265, abstract = {{We present CLARC (Cryptographic Library for Anonymous Reputation and Credentials), an anonymous credentials system (ACS) combined with an anonymous reputation system. Using CLARC, users can receive attribute-based credentials from issuers. They can efficiently prove that their credentials satisfy complex (access) policies in a privacy-preserving way. This implements anonymous access control with complex policies. Furthermore, CLARC is the first ACS that is combined with an anonymous reputation system where users can anonymously rate services. A user who gets access to a service via a credential, also anonymously receives a review token to rate the service. If a user creates more than a single rating, this can be detected by anyone, preventing users from spamming ratings to sway public opinion. To evaluate feasibility of our construction, we present an open-source prototype implementation.}}, author = {{Bemmann, Kai and Blömer, Johannes and Bobolz, Jan and Bröcher, Henrik and Diemert, Denis Pascal and Eidens, Fabian and Eilers, Lukas and Haltermann, Jan Frederik and Juhnke, Jakob and Otour, Burhan and Porzenheim, Laurens Alexander and Pukrop, Simon and Schilling, Erik and Schlichtig, Michael and Stienemeier, Marcel}}, booktitle = {{Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES '18}}, isbn = {{978-1-4503-6448-5}}, location = {{Hamburg, Germany}}, publisher = {{ACM}}, title = {{{Fully-Featured Anonymous Credentials with Reputation System}}}, doi = {{10.1145/3230833.3234517}}, year = {{2018}}, } @misc{3313, author = {{Maurer, Alexandra}}, publisher = {{Universität Paderborn}}, title = {{{Kundenbewertungen und Produktnachfrage: Eine ökonomische Analyse}}}, year = {{2018}}, } @misc{3314, author = {{Michels, Luisa Juliane}}, publisher = {{Universität Paderborn}}, title = {{{The Segmentation of Video-On-Demand Consumers}}}, year = {{2018}}, } @misc{3315, author = {{Walter, Miriam}}, publisher = {{Universität Paderborn}}, title = {{{Sentiment Analysis of User-generated Ratings in the Sharing Economy }}}, year = {{2018}}, } @misc{3316, author = {{Korn, Hanna}}, publisher = {{Universität Paderborn}}, title = {{{Restaurant reputation and meal prices: empricial evidence from the German restaurant industry}}}, year = {{2018}}, } @misc{3320, author = {{Rautenberg, Kai}}, publisher = {{Universität Paderborn}}, title = {{{Korrektheitsbeweise für Muster von Servicekompositionen}}}, year = {{2018}}, } @inproceedings{3345, abstract = {{Dynamically steering flows through virtualized net- work function instances is a key enabler for elastic, on-demand deployments of virtualized network functions. This becomes par- ticular challenging when stateful functions are involved, necessi- tating state management. The problem with existing solutions is that they typically embrace state migration and flow rerouting jointly, imposing a huge set of requirements on the on-boarded VNFs, e.g., solution-specific state management interfaces. In this paper, we introduce the seamless handover proto- col (SHarP). It provides an easy-to-use, loss-less, and order- preserving flow rerouting mechanism that is not fixed to a single state management approach. This allows VNF vendors to implement or use the state management solution of their choice. SHarP supports these solutions with additional information when flows are migrated. Further, we show how SHarP significantly reduces the buffer usage at a central (SDN) controller, which is a typical bottleneck in existing solutions. Our experiments show that SHarP uses a constant amount of controller buffer, irrespective of the time taken to migrate the VNF state.}}, author = {{Peuster, Manuel and Küttner, Hannes and Karl, Holger}}, booktitle = {{4th IEEE International Conference on Network Softwarization (NetSoft 2018)}}, location = {{Montreal}}, title = {{{ Let the state follow its flows: An SDN-based flow handover protocol to support state migration}}}, doi = {{10.1109/NETSOFT.2018.8460007}}, year = {{2018}}, } @inproceedings{3346, abstract = {{Developing a virtualized network service does not only involve the implementation and configuration of the network functions it is composed of but also its integration and test with management solutions that will control the service in its production environment. These integration tasks require testbeds that offer the needed network function virtualization infrastructure~(NFVI), like OpenStack, introducing a lot of management and maintenance overheads. Such testbed setups become even more complicated when the multi point-of-presence~(PoP) case, with multiple infrastructure installations, is considered. In this demo, we showcase an emulation platform that executes containerized network services in user-defined multi-PoP topologies. The platform does not only allow network service developers to locally test their services but also to connect real-world management and orchestration solutions to the emulated PoPs. During our interactive demonstration we focus on the integration between the emulated infrastructure and state-of-the-art orchestration solutions like SONATA or OSM.}}, author = {{Peuster, Manuel and Kampmeyer, Johannes and Karl, Holger}}, booktitle = {{4th IEEE International Conference on Network Softwarization (NetSoft 2018)}}, location = {{Montreal}}, title = {{{Containernet 2.0: A Rapid Prototyping Platform for Hybrid Service Function Chains}}}, doi = {{10.1109/NETSOFT.2018.8459905}}, year = {{2018}}, } @inproceedings{3347, abstract = {{Management and orchestration~(MANO) systems are the key components of future large-scale NFV environments. They will manage resources of hundreds or even thousands of NFV infrastructure installations, so called points of presence~(PoP). Such scenarios need to be automatically tested during the development phase of a MANO system. This task becomes very challenging because large-scale NFV testbeds are hard to maintain, too expensive, or simply not available. In this paper, we present a multi-PoP NFV infrastructure emulation platform that enables automated, large-scale testing of MANO stacks. We show that our platform can easily emulate hundreds of PoPs on a single physical machine and reduces the setup time of a test PoP by a factor of 232x compared to a DevStack-based test PoP installation. Further, we present a case study in which we test ETSI's Open Source MANO~(OSM) against our proposed system to gain insights about OSM's behaviour in large-scale NFV deployments.}}, author = {{Peuster, Manuel and Marchetti, Michael and Garcia de Blas, Gerado and Karl, Holger}}, booktitle = {{European Conference on Networks and Communications (EuCNC)}}, location = {{Ljubljana}}, title = {{{Emulation-based Smoke Testing of NFV Orchestrators in Large Multi-PoP Environments}}}, doi = {{10.1109/EuCNC.2018.8442701}}, year = {{2018}}, } @inproceedings{3362, abstract = {{Profiling applications on a heterogeneous compute node is challenging since the way to retrieve data from the resources and interpret them varies between resource types and manufacturers. This holds especially true for measuring the energy consumption. In this paper we present Ampehre, a novel open source measurement framework that allows developers to gather comparable measurements from heterogeneous compute nodes, e.g., nodes comprising CPU, GPU, and FPGA. We explain the architecture of Ampehre and detail the measurement process on the example of energy measurements on CPU and GPU. To characterize the probing effect, we quantitatively analyze the trade-off between the accuracy of measurements and the CPU load imposed by Ampehre. Based on this analysis, we are able to specify reasonable combinations of sampling periods for the different resource types of a compute node.}}, author = {{Lösch, Achim and Wiens, Alex and Platzner, Marco}}, booktitle = {{Proceedings of the International Conference on Architecture of Computing Systems (ARCS)}}, isbn = {{9783319776095}}, issn = {{0302-9743}}, pages = {{73--84}}, publisher = {{Springer International Publishing}}, title = {{{Ampehre: An Open Source Measurement Framework for Heterogeneous Compute Nodes}}}, doi = {{10.1007/978-3-319-77610-1_6}}, volume = {{10793}}, year = {{2018}}, } @misc{3365, author = {{Schnuer, Jan-Philip}}, publisher = {{Universität Paderborn}}, title = {{{Static Scheduling Algorithms for Heterogeneous Compute Nodes}}}, year = {{2018}}, } @misc{3366, author = {{Croce, Marcel}}, publisher = {{Universität Paderborn}}, title = {{{Evaluation of OpenCL-based Compilation for FPGAs}}}, year = {{2018}}, } @inproceedings{3373, abstract = {{Modern Boolean satisfiability solvers can emit proofs of unsatisfiability. There is substantial interest in being able to verify such proofs and also in using them for further computations. In this paper, we present an FPGA accelerator for checking resolution proofs, a popular proof format. Our accelerator exploits parallelism at the low level by implementing the basic resolution step in hardware, and at the high level by instantiating a number of parallel modules for proof checking. Since proof checking involves highly irregular memory accesses, we employ Hybrid Memory Cube technology for accelerator memory. The results show that while the accelerator is scalable and achieves speedups for all benchmark proofs, performance improvements are currently limited by the overhead of transitioning the proof into the accelerator memory.}}, author = {{Hansmeier, Tim and Platzner, Marco and Andrews, David}}, booktitle = {{ARC 2018: Applied Reconfigurable Computing. Architectures, Tools, and Applications}}, isbn = {{9783319788890}}, issn = {{0302-9743}}, location = {{Santorini, Greece}}, pages = {{153--165}}, publisher = {{Springer International Publishing}}, title = {{{An FPGA/HMC-Based Accelerator for Resolution Proof Checking}}}, doi = {{10.1007/978-3-319-78890-6_13}}, volume = {{10824}}, year = {{2018}}, } @article{3402, abstract = {{In machine learning, so-called nested dichotomies are utilized as a reduction technique, i.e., to decompose a multi-class classification problem into a set of binary problems, which are solved using a simple binary classifier as a base learner. The performance of the (multi-class) classifier thus produced strongly depends on the structure of the decomposition. In this paper, we conduct an empirical study, in which we compare existing heuristics for selecting a suitable structure in the form of a nested dichotomy. Moreover, we propose two additional heuristics as natural completions. One of them is the Best-of-K heuristic, which picks the (presumably) best among K randomly generated nested dichotomies. Surprisingly, and in spite of its simplicity, it turns out to outperform the state of the art.}}, author = {{Melnikov, Vitalik and Hüllermeier, Eyke}}, issn = {{1573-0565}}, journal = {{Machine Learning}}, title = {{{On the effectiveness of heuristics for learning nested dichotomies: an empirical analysis}}}, doi = {{10.1007/s10994-018-5733-1}}, year = {{2018}}, } @inproceedings{3414, abstract = {{Over the years, Design by Contract (DbC) has evolved as a powerful concept for program documentation, testing, and verification. Contracts formally specify assertions on (mostly) object-oriented programs: pre- and postconditions of methods, class invariants, allowed call orders, etc. Missing in the long list of properties specifiable by contracts are, however, method correlations: DbC languages fall short on stating assertions relating methods. In this paper, we propose the novel concept of inter-method contract, allowing precisely for expressing method correlations.We present JMC as a language for specifying and JMCTest as a tool for dynamically checking inter-method contracts on Java programs. JMCTest fully automatically generates objects on which the contracted methods are called and the validity of the contract is checked. Using JMCTest, we detected that large Java code bases (e.g. JBoss, Java RT) frequently violate standard inter-method contracts. In comparison to other verification tools inspecting (some) inter-method contracts, JMCTest can find bugs that remain undetected by those tools.}}, author = {{Börding, Paul and Haltermann, Jan Frederik and Jakobs, Marie-Christine and Wehrheim, Heike}}, booktitle = {{Proceedings of the IFIP International Conference on Testing Software and Systems (ICTSS 2018)}}, location = {{Cádiz, Spain}}, pages = {{39----55}}, publisher = {{Springer}}, title = {{{JMCTest: Automatically Testing Inter-Method Contracts in Java}}}, volume = {{11146}}, year = {{2018}}, } @inproceedings{3422, abstract = {{We study the consensus problem in a synchronous distributed system of n nodes under an adaptive adversary that has a slightly outdated view of the system and can block all incoming and outgoing communication of a constant fraction of the nodes in each round. Motivated by a result of Ben-Or and Bar-Joseph (1998), showing that any consensus algorithm that is resilient against a linear number of crash faults requires $\tilde \Omega(\sqrt n)$ rounds in an n-node network against an adaptive adversary, we consider a late adaptive adversary, who has full knowledge of the network state at the beginning of the previous round and unlimited computational power, but is oblivious to the current state of the nodes. Our main contributions are randomized distributed algorithms that achieve consensus with high probability among all except a small constant fraction of the nodes (i.e., "almost-everywhere'') against a late adaptive adversary who can block up to ε n$ nodes in each round, for a small constant ε >0$. Our first protocol achieves binary almost-everywhere consensus and also guarantees a decision on the majority input value, thus ensuring plurality consensus. We also present an algorithm that achieves the same time complexity for multi-value consensus. Both of our algorithms succeed in $O(log n)$ rounds with high probability, thus showing an exponential gap to the $\tilde\Omega(\sqrt n)$ lower bound of Ben-Or and Bar-Joseph for strongly adaptive crash-failure adversaries, which can be strengthened to $\Omega(n)$ when allowing the adversary to block nodes instead of permanently crashing them. Our algorithms are scalable to large systems as each node contacts only an (amortized) constant number of peers in each communication round. We show that our algorithms are optimal up to constant (resp.\ sub-logarithmic) factors by proving that every almost-everywhere consensus protocol takes $\Omega(log_d n)$ rounds in the worst case, where d is an upper bound on the number of communication requests initiated per node in each round. We complement our theoretical results with an experimental evaluation of the binary almost-everywhere consensus protocol revealing a short convergence time even against an adversary blocking a large fraction of nodes.}}, author = {{Robinson, Peter and Scheideler, Christian and Setzer, Alexander}}, booktitle = {{Proceedings of the 30th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, isbn = {{978-1-4503-5799-9/18/07}}, keywords = {{distributed consensus, randomized algorithm, adaptive adversary, complexity lower bound}}, location = {{Wien}}, title = {{{Breaking the $\tilde\Omega(\sqrt{n})$ Barrier: Fast Consensus under a Late Adversary}}}, doi = {{10.1145/3210377.3210399}}, year = {{2018}}, } @article{3510, abstract = {{Automated machine learning (AutoML) seeks to automatically select, compose, and parametrize machine learning algorithms, so as to achieve optimal performance on a given task (dataset). Although current approaches to AutoML have already produced impressive results, the field is still far from mature, and new techniques are still being developed. In this paper, we present ML-Plan, a new approach to AutoML based on hierarchical planning. To highlight the potential of this approach, we compare ML-Plan to the state-of-the-art frameworks Auto-WEKA, auto-sklearn, and TPOT. In an extensive series of experiments, we show that ML-Plan is highly competitive and often outperforms existing approaches.}}, author = {{Mohr, Felix and Wever, Marcel Dominik and Hüllermeier, Eyke}}, issn = {{1573-0565}}, journal = {{Machine Learning}}, keywords = {{AutoML, Hierarchical Planning, HTN planning, ML-Plan}}, location = {{Dublin, Ireland}}, pages = {{1495--1515}}, publisher = {{Springer}}, title = {{{ML-Plan: Automated Machine Learning via Hierarchical Planning}}}, doi = {{10.1007/s10994-018-5735-z}}, year = {{2018}}, } @inproceedings{3550, abstract = {{Nowadays companies like Apple create ecosystems of third- party providers and users around their software platforms. Often online stores like Apple App Store are created to directly market third-party solutions. We call such ecosystems store-oriented software ecosystems. While the architecture of these ecosystems is mainly derived from busi- ness decisions of their owners, ecosystems with greatly different archi- tectural designs have been created. This diversity makes it challenging for future ecosystem providers to understand which architectural design is suitable to fulfill certain business decisions. In turn, opening a plat- form becomes risky while endangering intellectual property or scarifying quality of services. In this paper, we identify three main design options of store-oriented software ecosystems by classifying existing ecosystems based on similarities in their business decisions. We elaborate on the design options, discuss their main contributions, and provide exemplary ecosystems. Our work provides aspiring ecosystem providers with the reusable knowledge of existing ecosystems and helps them to take more informed architectural decisions and reduce risks in future.}}, author = {{Jazayeri, Bahar and Zimmermann, Olaf and Engels, Gregor and Küster, Jochen and Kundisch, Dennis and Szopinski, Daniel}}, booktitle = {{Proceeding of International Symposium on Business Modeling and Software Design}}, isbn = {{9783319942131}}, issn = {{1865-1348}}, pages = {{390--400}}, publisher = {{Springer}}, title = {{{Design Options of Store-Oriented Software Ecosystems: An Investigation of Business Decisions}}}, doi = {{10.1007/978-3-319-94214-8_30}}, volume = {{319}}, year = {{2018}}, }