The paper entield "Weighted Rewriting: Semiring Semantics for Abstract Reduction Systems" by Emma Ahrens, Jan-Christoph Kassing, Jürgen Giesl and Joost-Pieter Katoen has been accepted for the 10th International Conference on Formal Structures for Computation and Deduction (FSCD 2025) in Birmingham (UK). This paper introduces a general semantics of the (possibly infinite) reduction sequences of an abstract reduction system in a semi-ring that is a complete lattice (for its natural ordering…
The paper entitled “Bayesian Inference in Quantum Programs” by Christina Gehnen, Dominique Unruh and Joost-Pieter Katoen has been accepted for presentation at the 52nd EATCS International Colloquium on Automata, Languages, and Programming (ICALP 2025 – Track B). This paper considers postselection in quantum physics (aka: Bayesian conditioning in programs), for quantum while-programs, defines an operational and denotational semantics over infinite-dimensional Hilbert spaces, and proves their…
The papers “Approximate Probabilistic Bisimulation for Continuous-Time Markov Chains” by Timm Spork, Christel Baier, Joost-Pieter Katoen, Sascha Klüppelholz, and Jakob Piribauer and “Efficient Probabilistic Model Checking for Relational Reachability” by Lina Gerlach, Tobias Winkler, Erika Ábrahám, Borzoo Bonakdarpour and Sebastian Junges have been accepted at the International Conference on Computer-Aided Verification (CAV) 2025. The first paper presents a new notion of approximate bisimulation…
The paper “Using GPUs And LLMs Can Be Satisfying for Nonlinear Real Arithmetic Problems” by Christopher Brix, Julia Walczak, Nils Lommen and Thomas Noll has been accepted for presentation at the VerifAI Workshop at ICLR 2025. The paper describes how satisfying assignments to quantifier-free NRA problems can be found using GPU acceleration, and how LLMs can be used to automatically generate efficient code for this purpose.
The paper “The Dial-a-Ride Problem in Primary Care with Flexible Scheduling” by Felix Engelhardt, Emma Ahrens, Christina Büsing together with Felix Rauh from University Leuven has been accepted for publication in the journal OR Spektrum. The paper generalizes the Dial-A-Ride problem, which models the transportation of patients in a rural area, such that it differentiates between chronic and walk-in patients. It proposes several heuristics for solving the generalized problem and shows their…
The paper entitled “Foundations for Deductive Verification of Continuous Probabilistic Programs: From Lebesgue to Riemann and Back” by Kevin Batz, Joost-Pieter Katoen, Francesca Randone (University of Trieste), and Tobias Winkler has been accepted for the International Conference on Object-Oriented Programming Systems, Languages, and Application (OOPSLA 2025). The paper presents a new technique to formally check bounds on the expected outcomes of probabilistic programs with continuous uniform…
The DFG together with the FNRS (Belgium) have granted the project, entitled “Mixing Formal Methods and Learning Techniques for Strategy Synthesis in Partially Observable Markov Decision Processes” for a period of three years. This project is a collaboration with the research group of Jean-Francois Raskin (Universite de Libre Bruxelles).
The paper “CERTPHASH: Towards Certified Perceptual Hashing via Robust Training” by Yuchen Yang (Johns Hopkins University), Qichang Liu (Tsinghua University), Christopher Brix, Huan Zhang (UIUC), and Yinzhi Cao (Johns Hopkins University) has been accepted for publication in the 34th USENIX Security Symposium. The paper proposes a novel technique to train neural networks to perform perceptual hashing (used to filter illicit images). Crucially, the networks are trained to be robust under evasion…
The paper entitled “An Oracle-Guided Approach to Constrained Policy Synthesis Under Uncertainty” by Roman Andriushchenko, Milan Češka, Filip Macák (Brno University of Technology), Sebastian Junges (Radboud University) and Joost-Pieter Katoen has been accepted for publication in the Journal of Artificial Intelligence Research (JAIR). The paper present coloured Markov Decision Processes (MDPs) which describes a collection of possible policy configurations with their structural dependencies. The…
The paper entitled “Quantifier Elimination and Craig Interpolation: The Quantitative Way” by Kevin Batz, Joost-Pieter Katoen and Nora Orhan has been accepted at the FoSSaCS 2025 Conference (Hamilton, Canada). This paper gives a quantifier elimination algorithm for quantitative formulas as they e.g. occur in the analysis of probabilistic programs, and present a theorem for a quantitative version of Craig interpolants.
The paper entitled “Fixed Point Certificates for Reachability and Expected Rewards in MDPs” by Tim Quatmann, Maximilian Schäffeler (TU Munich), Maximilian Weininger (ISTA), Tobias Winkler, Daniel Zilken and Krishnendu Chatterjee (ISTA) has been accepted at the 31st International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS 2025), to be held in Hamilton, Canada. This paper introduces novel approaches to certify reachability and expected rewards in MDPs.
The paper entitled “Robust Strategies for Stochastic Multi-Agent Systems” by Raphael Berthon, Joost-Pieter Katoen, Munyque Mittelmann, and Aniello Murano has been accepted as extended abstract at the 24th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2025), Detroit. The paper presents Probabilistic Alternating-Time Temporal Logic with bounded strategies (PATLb) for stochastic multi-agent systems with uncertainty, and considers robustness in strategy synthesis and…
The paper “Scalable Neural Network Verification with Branch-and-bound Inferred Cutting Planes” by Duo Zhou (University of Illinois Urbana-Champaign), Christopher Brix, Grani A Hanasusanto (Illinois) and Huan Zhang (Illinois) has been accepted for the Thirty-Eighth Annual Conference on Neural Information Processing Systems (NeurIPS 2024) in Vancouver. The paper describes how the branch-and-bound process in neural network verification can be used to extract cuts that reduce verification time by…
On the occasion of Joost-Pieter Katoen’s 60th birthday, a Colloquium on Principles of Verification was organised on November 7, 2024. It attracted more than 100 participants from all over the world and was opened by welcoming speeches by representatives of both the University of Twente (NL) and RWTH Aachen University. Moreover, it featured eleven scientific talks by renowned international researchers. A highlight was the handing over of no less than three volumes of a Festschrift published by…
The paper “A Taxonomy of Hoare-Like Logics: Towards a Holistic View using Predicate Transformers and Kleene Algebras with Top and Tests” by Lena Verscht and Benjamin Kaminski has been accepted for the 52nd ACM SIGPLAN Symposium on Principles of Programming Languages (POPL 2025) in Denver. The paper provides an overview of program logics, including Hoare logic and incorrectness logic, and discusses their relationships under assumptions such as termination or reversibility.