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TODAY UnRAVeL Survey Lecture: "Biggest Milestones"

by Kassing, Jan-Christoph

Dear all, this is a reminder for Jürgen Giesl's talk with the title "Proving Termination with Dependency Pairs" taking place today at 12:30 in the B-IT room 5053.2. Please find the details below --- Abstract --- Until 2000, techniques for automated termination analysis were mainly studied in the areas of logic programming and term rewrite systems (TRSs). However, the power of the available methods and tools was quite limited. In particular, the techniques were not modular and thus, they often failed when applying them to larger programs. Therefore, from 1996 onwards, we started to develop the so-called dependency pair technique to overcome these drawbacks. This technique then evolved into a general framework for modular termination proofs of term rewrite systems and is nowadays used in essentially all termination provers for term rewriting. By applying the dependency pair framework for TRSs as a backend, we also developed techniques for the automated termination analysis of many different programming languages, such as Java, Haskell, or Prolog. While notions like positive almost-sure termination originated in the TRS community, until recently there was hardly any technique available to analyze the termination behavior of probabilistic TRSs (PTRSs). Therefore, in very recent work we started to adapt the dependency pair framework to the probabilistic setting in order to analyze almost-sure termination of PTRSs as well. All these techniques are implemented in our tool AProVE. ---------------- Part of the programme of the research training group UnRAVeL is a series of lectures on the topics of UnRAVeL’s research thrusts algorithms and complexity, verification, logic and languages, and their application scenarios. Each lecture is given by one of the researchers involved in UnRAVeL. This years topic is "Biggest Milestones - Research at Its Peak", UnRAVeL professors will present the most important milestone of their respective research. All interested doctoral researchers and master students are invited to attend the UnRAVeL lecture series 2023 and engage in discussions with researchers and doctoral students. The next talk after today will not take place until June 15th. Then, Britta Peis is going to give a talk with the title "Ascending Auctions and Matroids" We are looking forward to seeing you at the lectures. Kind regards, Jan-Christoph for the organisation committee

2 days, 21 hours

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!!ABSAGE!!: Informatik-Oberseminar Dr. Jakob Bossek 24.05.2023

by Andrea Gibbels

Sehr geehrte Damen und Herren, aufgrund einer akuten Erkrankung von Herrn Dr. Bossek kann das für morgen angesetzte Oberseminar leider nicht stattfinden. Wir bedauern diese kurzfristige Absage und werden versuchen, zeitnah einen neuen Termin zu finden. Mit freundlichen Grüßen Im Auftrag Andrea Gibbels -- Andrea Gibbels, M.A. Administrative Assistant Chair for AI Methodology / Lehrstuhl für Methodik der Künstlichen Intelligenz RWTH Aachen University E-mail: secret(a)aim.rwth-aachen.de Phone: +49 241 80 21452 Theaterstr. 35-39 52062 Aachen Germany +********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Mittwoch, 24. Mai 2023, 13.00 Uhr Ort: Raum 9222, Gebäude E3, Ahornstr. 55 Referent: Dr. Jakob Bossek Lehrstuhl Informatik 14 Thema: Tailored Evolutionary Operators for the Multi-Objective Spanning Tree Problem Abstract: With this talk I want to introduce myself to the RWTH computer science department. In the first part I will go into detail on paper recently accepted in the evolutionary computation journal (Bossek & Grimme, 2023) entitled “Tailored Evolutionary Operators for the Multi-Objective Spanning Tree Problem”. The second part will give a broader overview of my research foci and projects in the fields of Evolutionary Optimisation and Automated Artificial Intelligence. The Minimum Spanning Tree (MST) problem is the challenge of finding a tree in an edge-weighted graph that maintains connectivity of all nodes and has minimal costs among all such trees. The MST problem is a fundamental combinatorial optimisation problem with countless applications, e.g., in the construction of communication networks, medical imaging, or many other areas that range from logistic via graph drawing to power grid network design. The basic single-objective version of the MST problem can be solved efficiently, i.e., in polynomial time, e.g., by Prim’s algorithm. The multi-objective MST (moMST) version though (i.e., multiple weights per edge) is NP-hard and suffers from intractability. Thus, efficient heuristics are needed to approximate the set of optimal trade-off solutions. Evolutionary Algorithms are randomised search heuristics that are among the most successful when it comes to solving NP-hard multi-objective optimisation problems. I will present recent work on the design of several highly biased sub-graph-based mutation operators for the moMST problem. In a nutshell, these operators replace (un)connected sub-trees of candidate solutions with locally (Pareto-)optimal sub-trees. The latter (biased) step is realised by applying Kruskal’s single-objective MST algorithm to a weighted sum scalarisation of a sub-graph. I will detail some runtime complexity results for the introduced operators and demonstrate results that show that the sub-graph based operators beat baseline algorithms from the literature even with severely restricted computational budget in terms of function evaluations on four different classes of complete graphs. Es laden ein: die Dozentinnen und Dozenten der Informatik

4 days, 18 hours

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Invitation to AI Colloquium event on 25. May

by Mann, Julia

Dear all, We'd like to announce our next AI colloquium which will take place on 25 May 2023, 4-6pm. Jens Kober, TU Delft, will present on "Robots Learning Through Interaction" (in English) in SuperC/Generali-Saal from 4-5pm. The talk will be held in person but also live streamed via Zoom. The event is free, but a registration is required, and the link can be found on our web page<https://www.ai.rwth-aachen.de/go/id/baofsc>. After the talk, there will be a networking session in the foyer with drinks and nibbles and all are welcome to stay. [cid:image002.png@01D9874E.DB9193D0] We kindly ask you to distribute this among your groups and students. Please feel free to use the attached slide. Thank you in advance. Julia Mann (part of the organising team) Dr Julia Mann Managing Director ______________________________________________ Center for Artificial Intelligence RWTH Aachen University Mies-van-der-Rohe-Strasse 15 office: 123 DE-52074 Aachen phone: +49-241-80 20757 Germany http://www.ai.rwth-aachen.de<http://www.ai.rwth-aachen.de/> [cid:image001.png@01D9872C.13EB5180]

1 week, 5 days

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Einladung Informatik-Oberseminar Dr. Jakob Bossek

by Andrea Gibbels

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Mittwoch, 24. Mai 2023, 13.00 Uhr Ort: Raum 9222, Gebäude E3, Ahornstr. 55 Referent: Dr. Jakob Bossek Lehrstuhl Informatik 14 Thema: Tailored Evolutionary Operators for the Multi-Objective Spanning Tree Problem Abstract: With this talk I want to introduce myself to the RWTH computer science department. In the first part I will go into detail on paper recently accepted in the evolutionary computation journal (Bossek & Grimme, 2023) entitled “Tailored Evolutionary Operators for the Multi-Objective Spanning Tree Problem”. The second part will give a broader overview of my research foci and projects in the fields of Evolutionary Optimisation and Automated Artificial Intelligence. The Minimum Spanning Tree (MST) problem is the challenge of finding a tree in an edge-weighted graph that maintains connectivity of all nodes and has minimal costs among all such trees. The MST problem is a fundamental combinatorial optimisation problem with countless applications, e.g., in the construction of communication networks, medical imaging, or many other areas that range from logistic via graph drawing to power grid network design. The basic single-objective version of the MST problem can be solved efficiently, i.e., in polynomial time, e.g., by Prim’s algorithm. The multi-objective MST (moMST) version though (i.e., multiple weights per edge) is NP-hard and suffers from intractability. Thus, efficient heuristics are needed to approximate the set of optimal trade-off solutions. Evolutionary Algorithms are randomised search heuristics that are among the most successful when it comes to solving NP-hard multi-objective optimisation problems. I will present recent work on the design of several highly biased sub-graph-based mutation operators for the moMST problem. In a nutshell, these operators replace (un)connected sub-trees of candidate solutions with locally (Pareto-)optimal sub-trees. The latter (biased) step is realised by applying Kruskal’s single-objective MST algorithm to a weighted sum scalarisation of a sub-graph. I will detail some runtime complexity results for the introduced operators and demonstrate results that show that the sub-graph based operators beat baseline algorithms from the literature even with severely restricted computational budget in terms of function evaluations on four different classes of complete graphs. Es laden ein: die Dozentinnen und Dozenten der Informatik -- Andrea Gibbels, M.A. Administrative Assistant Chair for AI Methodology / Lehrstuhl für Methodik der Künstlichen Intelligenz RWTH Aachen University E-mail: secret(a)aim.rwth-aachen.de Phone: +49 241 80 21452 Theaterstr. 35-39 52062 Aachen Germany

1 week, 5 days

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TODAY UnRAVeL Survey Lecture: "Biggest Milestones"

by Kassing, Jan-Christoph

Dear all, this is a reminder for Nils Nießen's talk with the title "Can Trains Be on Time?" taking place today at 12:30 in the B-IT room 5053.2. Please find the details below --- Abstract --- Why are trains always delayed and how is a delay defined at all? In the talk "Can trains be on time", the influences and conditions in the occurrence of delays in the railway system will be discussed. The distribution of buffer times has an influence on the propagation of delays. Using a two-train model, the mechanisms of delay propagation are derived. Approaches to increase punctuality and capacity are shown. ---------------- Part of the programme of the research training group UnRAVeL is a series of lectures on the topics of UnRAVeL’s research thrusts algorithms and complexity, verification, logic and languages, and their application scenarios. Each lecture is given by one of the researchers involved in UnRAVeL. This years topic is "Biggest Milestones - Research at Its Peak", UnRAVeL professors will present the most important milestone of their respective research. All interested doctoral researchers and master students are invited to attend the UnRAVeL lecture series 2023 and engage in discussions with researchers and doctoral students. Next week is no talk so that the next one will be held on the 25th May. Here, Jürgen Giesl is going to talk about "Proving Termination with Dependency Pairs". We are looking forward to seeing you at the lectures. Kind regards, Jan-Christoph for the organisation committee

2 weeks, 2 days

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Ankündigung: Informatik-Oberseminar Christopher Kugler

by Kugler, Christopher

+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Freitag, 19. Mai 2023, 13.00 Uhr Ort: Seminarraum 2202, Hauptbau, Ahornstr. 55 Referent: Christopher Kugler, M.Sc. Ehem. Lehrstuhl Informatik 11 Thema: Systematic Derivation of Feature-driven and Risk-based Test Strategies for Automotive Applications Abstract: The automotive industry is currently characterized by a disruptive change in terms of electro-mobility and highly autonomous driving. Similarly, new mobility concepts pose particular challenges for quality assurance measures in automotive product development. Traditional, experience-based approaches for deriving quality assurance strategies do not address these challenges and lead to potentially high failure rates during product operation. Therefore, a risk-based approach for the derivation of feature-specific test strategies is proposed in this thesis, which enables the objective definition of test end criteria and, through appropriate prioritization, an increase in the efficiency and effectiveness of performed verification and validation activities. On the basis of a two-stage risk assessment, quality assurance measures can initially be defined in early project phases and then be refined for individual product features as soon as required information is available. A framework for the derivation of test strategies is presented, which considers the current state of the art with regard to functional safety and distinguishes the applied acceptance thresholds for test-end criteria based on previously defined risk classes. The presented approach is evaluated in context of series development projects, where the significance of the risk assessment is verified through data analysis. The test strategy applied in those projects is retrospectively evaluated and compared against the risk-based approach presented in this thesis in terms of achieved effectiveness and efficiency. Finally, two different concepts for measuring quality of automotive products are introduced and profound product release criteria are defined. Es laden ein: die Dozentinnen und Dozenten der Informatik

2 weeks, 6 days

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TODAY UnRAVeL Survey Lecture: "Biggest Milestones"

by Kassing, Jan-Christoph

Dear all, this is a reminder for Sebastian Trimpe's talk with the title "Event-Triggered Learning" taking place today at 12:30 in the B-IT room 5053.2. Please find the details below --- Abstract --- The ability to learn is an essential aspect of autonomous systems facing uncertain and changing environments. However, the process of learning a new model or behavior often does not come for free, but involves a certain cost. For example, gathering informative data often means to deviate from normal operation, it may be challenging due to physical limitations, or updating models can require substantial computation. Hence, the question of "when to learn?" is essential for the efficient and persistent operation of autonomous systems. In this talk, I will be discussing recent research on the concept of event-triggered learning (ETL), which we have proposed for making principled decisions on when to learn a new dynamics model or controller. We will present some specific trigger designs that trigger learning when needed, and also highlight experimental application leading to significant resource savings. Moreover, I will give a personal "historical" perspective and trace back, how our recent research was itself triggered by my own PhD research and papers. I will also dare to look into the future and discuss what potential "milestone" papers there might still be to come. ---------------- Part of the programme of the research training group UnRAVeL is a series of lectures on the topics of UnRAVeL’s research thrusts algorithms and complexity, verification, logic and languages, and their application scenarios. Each lecture is given by one of the researchers involved in UnRAVeL. This years topic is "Biggest Milestones - Research at Its Peak", UnRAVeL professors will present the most important milestone of their respective research. All interested doctoral researchers and master students are invited to attend the UnRAVeL lecture series 2023 and engage in discussions with researchers and doctoral students. Next week, Nils Nießen is going to give a talk with the title "Can Trains Be on Time?" We are looking forward to seeing you at the lectures. Kind regards, Jan-Christoph for the organisation committee

3 weeks, 2 days

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TODAY UnRAVeL Survey Lecture: "Biggest Milestones"

by Kassing, Jan-Christoph

Dear all, this is a reminder for Christina Büsing's talk with the title "Robust Strategic Planning for Mobile Medical Units" taking place today at 12:30 in the B-IT room 5053.2. Please find the details below --- Abstract --- Mobile medical units (MMUs) allow for an efficient medical coverage of sparsely populated, spacious areas. Unfortunately, flexibility comes at the price of a highly complex operation planning process. In this talk, we investigate the strategic planning of an MMU service by deciding where MMU operation sites should be set up and how often these should be serviced. To that end, we study the strategic planning problem for MMUs (SPMMU) – a capacitated set covering problem that includes existing practices and two types of patient demands: (i) steerable demands representing patients who seek health services through a centralized appointment system and can be steered to any treatment facility within a given consideration set and (ii) unsteerable demands representing walk-in patients who always visit the closest available treatment facility. We propose an integer linear program for the SPMMU that can be solved via Benders decomposition and constraint generation. All our results transfer to the session-specific SPMMU and we evaluate our models in a computational study based on a set of instances generated from a rural primary care system in Germany. ---------------- Part of the programme of the research training group UnRAVeL is a series of lectures on the topics of UnRAVeL’s research thrusts algorithms and complexity, verification, logic and languages, and their application scenarios. Each lecture is given by one of the researchers involved in UnRAVeL. This years topic is "Biggest Milestones - Research at Its Peak", UnRAVeL professors will present the most important milestone of their respective research. All interested doctoral researchers and master students are invited to attend the UnRAVeL lecture series 2023 and engage in discussions with researchers and doctoral students. Next week, Sebastian Trimpe is going to give a talk with the title "Event-Triggered Learning" We are looking forward to seeing you at the lectures. Kind regards, Jan-Christoph for the organisation committee

1 month

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TODAY UnRAVeL Survey Lecture: "Biggest Milestones"

by Kassing, Jan-Christoph

Dear all, this is a reminder for Martin Grohe's talk with the title "The Quest for a Logic Capturing PTIME" taking place today at 12:30 in the B-IT room 5053.2. Please find the details below --- Abstract --- Problems that are hard to describe are hard to solve and vice versa." This claim may seem naive or just wrong at first sight, but it is the underlying idea of a deep and fruitful connection between the descriptive complexity and the computational complexity of computational problems. Here descriptive complexity refers to the “language resources” required to express a problem in a formal language, or logic whereas computational complexity refers to the computational resources needed to solve the problem. There are logical characterisations of many common complexity classes such as NP or PSPACE, but the question of whether there is a logical characterisation of the class PTIME of polynomial time solvable problems remains open. It was first asked by Chandra and Harel (1982) in the context of database theory, and later in a slightly different form by Gurevich (1988) in the context of finite model theory. In this talk, I will review the question and speak about negative as well as positive results spanning the last 40 years. ---------------- Part of the programme of the research training group UnRAVeL is a series of lectures on the topics of UnRAVeL’s research thrusts algorithms and complexity, verification, logic and languages, and their application scenarios. Each lecture is given by one of the researchers involved in UnRAVeL. This years topic is "Biggest Milestones - Research at Its Peak", UnRAVeL professors will present the most important milestone of their respective research. All interested doctoral researchers and master students are invited to attend the UnRAVeL lecture series 2023 and engage in discussions with researchers and doctoral students. Next week, Christina Büsing is going to give a talk with the title "Robust Strategic Planning for Mobile Medical Units" We are looking forward to seeing you at the lectures. Kind regards, Jan-Christoph for the organisation committee

1 month, 1 week

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TODAY UnRAVeL Survey Lecture: "Biggest Milestones"

by Kassing, Jan-Christoph

Dear all, this is a reminder for Erika Ábrahám's talk with the title "Building Bridges between Symbolic Computation and Satisfiability Checking" taking place today at 12:30 in the B-IT room 5053.2. Please find the details below ------ The use of advanced methods to solve practical and industrially relevant problems by computers has a long history. Symbolic Computation is concerned with the algorithmic determination of exact solutions to complex mathematical problems. More recent developments in the area of Satisfiability Checking started to tackle similar problems but with different algorithmic and technological solutions. Though both communities have made remarkable progress in the last decades, they need to be further strengthened to tackle practical problems of ever increasing size and complexity. Their separate tools (computer algebra systems and SMT solvers) are urgently needed to address prevailing problems having a direct effect on our society. For example, Satisfiability Checking is an essential backend for assuring the security and the safety of computer systems. In various scientific areas, Symbolic Computation is able to deal with large mathematical problems far beyond the scope of pencil and paper solutions. Until recently, the two communities have been largely disjoint and unaware of the achievements of one another, despite there being strong reasons for them to discuss and collaborate, since they share many central interests. Researchers from these two communities rarely interacted, and also their tools lack common, mutual interfaces for unifying their strengths. As said, until recently... ------ Part of the programme of the research training group UnRAVeL is a series of lectures on the topics of UnRAVeL’s research thrusts algorithms and complexity, verification, logic and languages, and their application scenarios. Each lecture is given by one of the researchers involved in UnRAVeL. This years topic is "Biggest Milestones - Research at Its Peak", UnRAVeL professors will present the most important milestone of their respective research. All interested doctoral researchers and master students are invited to attend the UnRAVeL lecture series 2023 and engage in discussions with researchers and doctoral students. Next week, Martin Grohe is going to give a talk with the title "The Quest for a Logic Capturing PTIME" We are looking forward to seeing you at the lectures. Kind regards, Jan-Christoph for the organisation committee

1 month, 2 weeks

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