Past Events

In this work, we focus on representation of models of Dynamic Epistemic Logic (DEL) which traditionally relies on standard Kripke models, where possible worlds are linked by indistinguishability relations, each defined with respect to an agent, to model knowledge dynamics. However, the DEL model-checking problem, known to be PSPACE-complete, faces practical challenges due to the large size of these models, which can grow exponentially with the number of propositions in the worst case. Two independent approaches address this issue by proposing more compact representations: one uses knowledge structures based on Binary Decision Diagrams (BDDs), while the other utilizes regular expression-like Mental Programs. Both methods offer succinct representations of Kripke models and enable PSPACE-efficient model-checking.

This is a joint work with Gregor Behnke (ILLC, UvA), Malvin Gattinger (ILLC, UvA) and Haitian Wang (ILLC, UvA).

In this work, we focus on representation of models of Dynamic Epistemic Logic (DEL) which traditionally relies on standard Kripke models, where possible worlds are linked by indistinguishability relations, each defined with respect to an agent, to model knowledge dynamics. However, the DEL model-checking problem, known to be PSPACE-complete, faces practical challenges due to the large size of these models, which can grow exponentially with the number of propositions in the worst case. Two independent approaches address this issue by proposing more compact representations: one uses knowledge structures based on Binary Decision Diagrams (BDDs), while the other utilizes regular expression-like Mental Programs. Both methods offer succinct representations of Kripke models and enable PSPACE-efficient model-checking.

This is a joint work with Gregor Behnke (ILLC, UvA), Malvin Gattinger (ILLC, UvA) and Haitian Wang (ILLC, UvA).

Abstract: In this talk, we will consider constraints over the domain of finite strings. Constraint system typically involve relational constraints and membership constraints. In our setting, we consider sub-word relation for relating the variables. We will study the satisfiability problem for such constraint systems. While the problem in full generality is undecidable, we will consider an acyclic fragment of it and show decidability. We show that the problem is uniformly NExptime-complete when regular or context free languages are involved in the membership constraints. We will further establish a close connection between this problem and reachability in certain kinds of lossy channel systems.  This is joint work with C Aiswarya and Soumodev Mal.

Abstract: Nyaya shastra, which is one of the darshanas of Indian philosophy, deals with a wide variety of philosophical topics. Chief among them is the study of epistemology and means of knowledge, with special emphasis on inference. In these lectures, we will give a broad introduction to Nyaya and present some aspects of reasoning according to Nyaya. The talks will be at a beginner's level.

Abstract: Nyaya shastra, which is one of the darshanas of Indian philosophy, deals with a wide variety of philosophical topics. Chief among them is the study of epistemology and means of knowledge, with special emphasis on inference. In these lectures, we will give a broad introduction to Nyaya and present some aspects of reasoning according to Nyaya. The talks will be at a beginner's level.

Abstract:Typically, multiple reasoners are modeled by indexed modalities in modal logics. Even though iterated modalities—as in Kᵢ Kⱼ α—might suggest that agent i knows agent j and that agent j knows α, the former assertion lies outside the scope of the modality itself. However, the notion of agency itself calls for logical study, and we can look for logical structure in agents as well. We will discuss a range of questions related to modal reasoning about agency and agent identity, in the hope that new lines of research may lead to more satisfactory answers than we have now.