- informatik-vortraege - lists.rwth-aachen.de

Einladung: Informatik-Oberseminar Richard Wilke
by Richard Wilke 14 Jul '21

14 Jul '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Freitag, 23. Juli 2021, 10:00 Uhr Zoom: https://rwth.zoom.us/j/97181863376?pwd=VmZIUzlNTXhQRFl0S25uRFBTRW0wdz09 Meeting-ID: 971 8186 3376 Kenncode: 867315 Referent: Richard Wilke, M.Sc. LuFG Mathematische Grundlagen der Informatik Thema: Reasoning about Dependence and Independence: Teams and Multiteams Abstract: Team semantics is the mathematical basis of modern logics for reasoning about dependence and independence. Its core feature is that formulae are evaluated against a set of assignments, called a team. This approach dates back to Hodges (1997) who used it to provide a compositional semantics for independence friendly logic. Building on this idea, Väänänen (2007) suggested that dependencies between variables should not be treated as annotations of quantifiers, but as atomic properties of teams. However, being based on sets, team semantics can only be used to reason about the presence or absence of data. Multiteam semantics instead takes multiplicities of data into account and is based on multisets of assignments, called multiteams. In this talk we give an overview of this formalism, explore a wide spectrum of logics with multiteam semantics and compare them with regard to their expressive power. We exhibit some striking differences between multiteam and team semantics, and also show where these formalisms are similar. Moreover, we present a game-theoretic semantics for our logic and establish connections between logics with multiteam semantics and variants of existential second-order logic. Es laden ein: die Dozentinnen und Dozenten der Informatik

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Einladung Informatik-Oberseminar Evgeny Kusmenko
by Kusmenko, Evgeny 06 Jul '21

06 Jul '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Montag, 19. Juli 2021, 14.30 Uhr Zoom: https://rwth.zoom.us/j/99446295120?pwd=NWU0QmIvVkpONlV2R0xmbmloTkhZZz09 Referent: Dipl.-Ing. Evgeny Kusmenko Lehrstuhl Informatik 3 Thema: Model-Driven Development Methodology and Domain-Specific Languages for the Design of Artificial Intelligence in Cyber-Physical Systems Abstract: The development of cyber-physical systems poses a multitude of challenges requiring experts from different fields. Such systems cannot be developed successfully without the support of appropriate processes, languages, and tools. Model-driven software engineering is an important approach which helps development teams to cope with the increasing complexity of today's cyber-physical systems. In this talk we are going to discuss a model-driven engineering methodology with a particular focus on interconnected intelligent cyber-physical systems such as cooperative vehicles. The basis of the proposed methodology is a component-and-connector architecture description language focusing on the decomposition and integration of cyber-physical system software. It features a strong, math-oriented type system abstracting away from the technical realization and incorporating physical units. To facilitate the development of highly-interconnected self-adaptive systems, the language enables its users to model component and connector arrays and supports architectural runtime-reconfiguration. Architectural elements can be altered, added, and removed dynamically upon the occurrence of trigger events. In order to fully cover the development process, the proposed methodology, in addition to structural modeling, provides means for behavior specification and its seamless integration into the components of the architecture. A matrix-oriented scripting language enables the developer to specify algorithms using a syntax close to the mathematical domain. What is more, a dedicated deep learning modeling language is provided for the development and training of neural networks as directed acyclic graphs of neuron layers. The framework supports different learning methods including supervised, reinforcement, and generative adversarial learning, covering a broad range of applications from image and natural language processing to decision making and test data generation. The presented toolchain enables an automated generation of fully functional C++ code together with the corresponding build and training scripts based on the architectural models and behavior specifications. Finally, to facilitate the integration and deployment of the modeled software in distributed environments, we use a tagging approach to model the middleware and to control a middleware generation toolchain. Es laden ein: die Dozentinnen und Dozenten der Informatik

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Einladung: Informatik-Oberseminar Patrick Landwehr
by Landwehr, Patrick 05 Jul '21

05 Jul '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Mittwoch, 14. Juli 2021, 10.00 Uhr Ort: Zoom Videokonferenz Link: https://rwth.zoom.us/j/94853770165?pwd=Uzk4TjI4TGNJQ3owaXJDbUxMT2d0UT09 Meeting-ID: 948 5377 0165 Kenncode: 046795 Referent: Patrick Landwehr M.Sc. Lehrstuhl Informatik 7 Thema: Tree Automata with Constraints on Infinite Trees Abstract: Tree automata on infinite trees are a powerful tool that is widely used for decision procedures and synthesis of logical specifications. It is well known that finite tree automata have good algorithmic properties, but somewhat limited expressive power. For example, they cannot verify that certain subtrees of an input tree are equal. In order to model such properties, we study extensions of tree automata that use so called constraints to compare whole subtrees of an input. We distinguish between two types of constraints: local constraints and global constraints. Local constraints can be used to compare the direct subtrees of each node. In this thesis we first summarize the existing results of tree automata with local constraints for infinite trees. Then we paritally answer the open question whether the class of languages recognizable by these automata is closed under projection. That is, we show that in the case of automata with Büchi acceptance condition the class of recognizable languages is closed under projection. As a consequence, we obtain a new decision algorithm for the emptiness problem as well as a proof for the fact that each non-empty language recognized by a Büchi tree automaton with sibling constraints contains a regular tree. Moreover, we also study logical characterizations of this class of languages. Tree automata with global constraints are able to compare compare subtrees whose positions are defined by the states reached in a run. For example, this model can verify that all subtrees rooted at positions where a certain state is reached are equal. In this thesis we generalize the model introduced on finite trees to the setting of infinite trees. We show that most closure properties and decidability results can be extended from finite to infinite trees. However, new techniques are required in order to do so. While the decidability of the emptiness problem remains an open question in general, we present decidability results for some subclasses of tree automata with global constraints. That is, if the automaton tests only for equality of subtrees (and not for inequality) the emptiness problem is decidable. The same is true if the underlying language (i.e. when ignoring the constraints) is countable. We also study the special case of automata with global constraints on unary infinite trees (omega-words). Here we show that in contrast to branching trees, the class of languages recognizable by these automata is closed under complement. Finally, we present precise logical characterizations for all of the subclasses mentioned, by extensions of monadic second order logic on infinite trees (or omega-words). Es laden ein: die Dozentinnen und Dozenten der Informatik

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Einladung: Informatik-Oberseminar Andrea Schnorr
by Andrea Schnorr 03 Jul '21

03 Jul '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Freitag, 19. Februar 2021, 11.00 Uhr Zoom: https://rwth.zoom.us/j/2452218628 Referent: Andrea Schnorr, M.Sc. LuFG i12 Thema: Feature Tracking for Space-Filling Structures Abstract: Feature-based visualization is a proven strategy to deal with the massive amounts of data emerging from time-dependent simulations: the analysis focuses on meaningful structures, i.e., said features. Feature tracking algorithms aim at automatically finding corresponding objects in successive time steps of these time-dependent data sets in order to assemble the individual objects into spatio-temporal features. Classically, feature-based visualization has focused on sparse structures, i.e. structures which cover only a small portion of the data domain. Given a sufficiently high temporal resolution, existing tracking approaches are able to reliably resolve the correspondence between feature objects of successive time steps. Our research is motivated by our collaborators' work on the statistical analysis of structures that are space-filling by definition: dissipation elements. Space-filling structures partition the entire domain. Our collaborators aim at extending their statistical analysis to a time-dependent setting. Hence, we introduce an efficient approach for general feature tracking which handles both sparse and space-filling data. To this end, we develop a framework for automatic evaluation of tracking approaches, an algorithmic framework for feature tracking, and an efficient implementation of this framework. First, we propose a novel evaluation framework based on algorithmic data generators, which provide synthetic data sets and the corresponding ground truth data. This framework facilitates the structured quantitative analysis of an approach's feature tracking performance and the comparison of different approaches based on the resulting measurements. Second, we introduce a novel approach for tracking both sparse and space-filling features. The correspondence between neighboring time-steps is determined by successively solving two graph optimization problems. In the first phase, one-to-one assignments are resolved by computing a maximum-weight, maximum-cardinality matching on a bi-partite graph. In its second phase, the algorithm detects events by finding a maximum weight independent set in a graph of all possible, potentially conflicting event explanations. Third, we show an optimized version of the second stage of the tracking framework which exploits the model-specific graph structure arising for the tracking problem. The method's effectiveness is demonstrated by a set of case studies including the use of the evaluation framework as well as the analysis of miscellaneous real-world simulation data sets. Es laden ein: die Dozentinnen und Dozenten der Informatik

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Einladung: Informatik-Oberseminar Herr Peter Marcel de Lange
by Leany Maaßen 17 Jun '21

17 Jun '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Dienstag, 20. Juli 2021, 10:00-11:00 Uhr Zoom: <https://rwth.zoom.us/j/93538347394?pwd=YXlqZ1VqSE0vRjRnclRtQTY5RVJOZz09> https://rwth.zoom.us/j/93538347394?pwd=YXlqZ1VqSE0vRjRnclRtQTY5RVJOZz09 Meeting-ID: 935 3834 7394 Kenncode: 388699 Referent: Herr Peter Marcel de Lange, M.Sc. Lehrstuhl Informatik 5 Thema: Scaffolding Decentralized Community Information Systems for Lifelong Learning Communities Abstract: With the rise of the Web 2.0, social networking sites and content management systems enabled professional communities to create Web content. But it simultaneously put the communities at the mercy of the platform operators and software providers. Decentralized community information systems bring in a new perspective by offering self-hosting, self-governing and self-developing communities. In this dissertation, we followed a design science approach that provides support for communities to create and host their own, decentralized community information systems. On the one hand, we produced several artifacts to provide possible answers to the question of what properties such an infrastructure needs to fulfill. On the other hand, we transfer the metaphor of educational scaffolding to the domain of service development. We demonstrated and evaluated our open source artifacts on a European scale, with three longitudinal studies conducted within several communities from different areas of technology enhanced learning, such as the European voluntary service, vocational and educational training providers and in higher education mentoring scenarios. Es laden ein: die Dozentinnen und Dozenten der Informatik _______________________________ Leany Maaßen RWTH Aachen University Lehrstuhl Informatik 5, LuFG Informatik 5 Prof. Dr. Stefan Decker, Prof. Dr. Matthias Jarke, Prof. Gerhard Lakemeyer Ph.D. Ahornstrasse 55 D-52074 Aachen Tel: 0241-80-21509 Fax: 0241-80-22321 E-Mail: maassen(a)dbis.rwth-aachen.de

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Ankündigung: Informatik-Oberseminar
by Thönnessen, David 15 Jun '21

15 Jun '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Montag, 21. Juni 2021, 13.00 Uhr Ort: Videokonferenz (Zoom-Meeting, Informationen siehe unten) Referent: David Thönnessen, M.Sc. Lehrstuhl Informatik 11 Thema: Hardware-in-the-Loop Testing of Industrial Automation Systems Using PLC Languages Abstract: Testing industrial controllers such as Programmable Logic Controllers (PLCs) poses specific challenges to the test process. Especially in the context of Cyber-Physical Production System (CPPS) the control systems are subject to continuous reconfiguration. Therefore, it is no longer sufficient to test solely before commissioning, but it must be possible to test existing control systems after their reconfiguration with low effort and to put them back into operation. Our approach for this is to develop a test environment that allows an efficient and modular test case specification and can therefore be easily adapted to changing environmental conditions. We have chosen Hardware-in-the-Loop (HiL) simulation as the basis for this test environment since not only the control model or control program is included in the test, but also the control hardware. Our architecture uses slightly extended PLC programming languages to specify test cases. Thus, we avoid the change in methodology that occurs when using dedicated test case specification languages and corresponding test environments. Furthermore, we have provided our concept with the possibility of randomized test case generation, such that a large number of test cases can be generated and tested without a tester having to specify them manually. Our hypothesis is that this will lead to faster and more reliable customizable test cases and thus create the desired agility. The evaluation of our implementation shows that especially developers who are familiar with PLC programming languages can achieve an increase in testing efficiency compared to existing test tools. Furthermore, by randomized testing of Safety Programmable Logic Controllers (Safety PLCs), we show that our test tool can find critical errors in control systems, which would have been found with traditional test methods only to a limited extent. From these results we conclude that the concept presented here is a valuable addition to existing test methods and well-tailored to the challenges of CPPS. Es laden ein: die Dozentinnen und Dozenten der Informatik +********************************************************************** Thema: PhD Defense David Thönnessen Uhrzeit: 21.Juni.2021 01:00 PM Amsterdam, Berlin, Rom, Stockholm, Wien Zoom-Meeting beitreten https://rwth.zoom.us/j/96024814962?pwd=eEU5SmNFTjYyWitJVldVRmQ3TE5pdz09 Meeting-ID: 960 2481 4962 Kenncode: 158094 +**********************************************************************

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Einladung: Informatik-Kolloquium Prof. Stephan Günnemann, 15. Juni um 14h
by Gerhard Lakemeyer 09 Jun '21

09 Jun '21

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Einladung: Informatik-Oberseminar Herr Sevket Gökay
by Leany Maaßen 02 Jun '21

02 Jun '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Dienstag, 15. Juni 2021, 14:00-15:00 Uhr Zoom: https://rwth.zoom.us/j/95286197657?pwd=TWtHZHBpa3Q4bmNIZUZXZ21NSmdydz09 Meeting-ID: 952 8619 7657 Kenncode: 048149 Referent: Herr Dipl.-Inform. Sevket Gökay Lehrstuhl Informatik 5 Thema: Scalable Real-Time Ride-Sharing with Meeting Points for Flexible On-Demand Public Transportation Abstract: The landscape of personal transportation is colorful and ever-changing. Ride-sharing, a member of the on-demand transportation family, sits between the private and public transportation categories. It can transport multiple passengers with similar journeys in the same vehicle in a flexible and convenient manner. This work explores real-time ride-sharing in three steps. First, we develop and evaluate a dynamic (i.e. flexible, on-demand) bus-like service as an alternative to the traditional bus service in rural areas with low demand. Simulations conducted in Aachen and in Ulm indicate that both the providers and the customers might benefit from this alternative. Next, we address the computational scalability issue of the service in urban areas with high demand. We present an approach to reduce processing time by employing an improved trip-vehicle fitness heuristic. The evaluation simulates New York City taxi trips in a ride-sharing context, and exhibits significant performance improvement, together with improved customer satisfaction and vehicle costs. Finally, we investigate the prevention of small detours of vehicles, by merging location visits with close proximity into one by introducing small walking paths. The results hint at a significant increase in the number of satisfied trip requests. Es laden ein: die Dozentinnen und Dozenten der Informatik _______________________________ Leany Maaßen RWTH Aachen University Lehrstuhl Informatik 5, LuFG Informatik 5 Prof. Dr. Stefan Decker, Prof. Dr. Matthias Jarke, Prof. Gerhard Lakemeyer Ph.D. Ahornstrasse 55 D-52074 Aachen Tel: 0241-80-21509 Fax: 0241-80-22321 E-Mail: maassen(a)dbis.rwth-aachen.de

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Einladung: Informatik-Oberseminar Daniel Wiebking
by Daniel Wiebking 01 Jun '21

01 Jun '21

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Montag, 14. Juni 2021, 16:00 Uhr Ort: Zoom Videokonferenz Link: https://rwth.zoom.us/j/94470149252?pwd=ZnYwVXQrbStveVdDNDk1V1BlN1lJUT09 Meeting-ID: 944 7014 9252 Kenncode: 004247 Referent: Daniel Wiebking, M.Sc. Lehrstuhl Informatik 7 Thema: A Decomposition-Compatible Canonization Framework for the Graph Isomorphism Problem Abstract: The Graph Isomorphism Problem is one of a few famous problems in NP that is neither known to be solvable in polynomial time nor to be NP-complete. The problem asks whether two given input graphs are structurally equivalent, which means that both graphs coincide up to a renaming of the vertices. With Babai's celebrated breakthrough (STOC 2016) it was shown that the problem can be decided in quasipolynomial time. One way of solving the Graph Isomorphism Problem is by applying a canonization approach. Graph canonization is the task of transforming a graph into a canonical form, that is, a graph representation that coincides for structurally equivalent graphs. As far as we know, graph canonization might be harder than the Graph Isomorphism Problem. In particular, there are isomorphism tests for various graph classes and objects for which to date no canonization algorithm with the same asymptotic running time is known. In this thesis, we devise a unified canonization framework for graphs, and beyond that for combinatorial objects in general. We use that framework to design new fastest canonization algorithms with an asymptotic running time matching the best known isomorphism tests. Our framework supports the use of decomposition techniques. By combining our framework with new graph-theoretic decompositions, we not only match but even improve the running time of existing isomorphism tests for graphs of bounded treewidth and graphs excluding fixed minors. Our improved algorithms for restricted graph classes come hand in hand with new insights about the automorphism groups. We prove several restrictions on these groups by analyzing them from a purely mathematical point of view. Beyond that, our decomposition-friendly framework has also applications in computational group theory. In particular, we design a new fastest algorithm computing normalizers of permutation groups. Finally, we investigate the connections between isomorphism testing and canonization from a logical perspective. To this end, we provide a new computation model that supports a construction turning isomorphism tests into canonization algorithms. Es laden ein: die Dozentinnen und Dozenten der Informatik

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Einladung: Informatik-Kolloquium Holger Hoos
by Martin Grohe 31 May '21

31 May '21

********************************************************************** * * * Einladung * * * * Informatik-Kolloquium * * * ********************************************************************** Zeit: Dienstag, 8. Juni 2021, 14:00 Uhr Ort: https://rwth.zoom.us/j/98025555800?pwd=SUgxYWR3RGxnaGNMZGg5bmNqeGZYQT09 Meeting-ID: 980 2555 5800 Kenncode: 419493 ********************************************************************** Vortragender: Holger H. Hoos (Universität Leiden) Titel: Cooperative competition: A new way of solving computationally challenging problems in AI and beyond Abstract: Progress in solving challenging problems in artificial intelligence, computer science at large, and beyond is driven, to a significant extent, by competition - regular algorithm competitions as well as comparative performance evaluation against state-of-the-art methods from the literature. A prominent example for this is the satisfiability problem in propositional logic (SAT), an NP-hard problem that not only lies at the foundations of computer science, but also plays a key role in many real-world applications, notably in ensuring the correctness of hard- and software. In this presentation, I will argue that it is time to rethink the way we assess the state of the art in solving problems such as SAT and the incentives for improving it. I will demonstrate how automated algorithm selection and configuration techniques based on sophisticated machine learning and optimisation methods have fundamentally changed not only the state of the art in solving SAT and many other NP-hard problems, but also provide a natural basis for cooperative competition - a new approach for achieving and assessing progress not merely in solving these problems, but also in the way we approach them as a scientific community. Es laden ein: die Dozentinnen und Dozenten der Informatik

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