Lista referatów

• 2023-01-11, godz. 14:15, 5050

  Pierre Ohlmann (MIM UW)

  Memory in games and universal graphs

  I will present recent characterisations of positionality and finite memory in infinite duration games by means of universal graphs. The goal is to derive properties of games with a given objective W by understanding the structure of graphs satisfying W (meaning that all path colorations belong to W)...

• 2022-12-21, godz. 14:15, 5050

  Marcin Przybyłko (University of Leipzig)

  Enumerating Answers to Ontology Mediated Queries

  A known dichotomy states that for conjunctive queries (CQs) with no self-joins the set of answers can be enumerated with linear preprocessing* and constant delay* if and only** if the query is both acyclic and free-connex. I will show how to lift those results to the enumeration of certain answer...

• 2022-12-14, godz. 14:15, 5050

  Antonio Casares Santos (LaBRI, Université de Bordeaux)

  A correspondence between memory and automata for Muller languages

  In this talk, we will be interested in infinite-duration games using Muller winning conditions, that is, the objective of such games is given by a boolean combination of colors that have to appear infinitely often. In Muller games, finite memory strategies suffice, meaning that Eve can play optimall...

• 2022-12-07, godz. 14:15, 5050

  Lorenzo Clemente (MIM UW)

  Decidability of equivalence of deterministic one-way multitape finite automata

  I will present an old decidability result by Harju and Karhumäki, as in the title. The original proof involves some very nice algebraic constructions, which constitute the motivation for this presentation. We start from the well-known problem of deciding equivalence of one-dimensional linear recu...

• 2022-11-30, godz. 14:15, 5050

  David Purser (MIM UW)

  The big-O problem for max-plus automata

  Given two weighted automata A and B over the (N, max, plus) semi-ring we consider the problem of deciding whether there exists a constant c such that A(w) ≤ c B(w) + c for every word w. The problem is known as the big-O problem or affine domination. The problem is a relaxation of the containment p...

• 2022-11-23, godz. 14:15, 5050

  Jakob Piribauer (TU Dresden)

  Tradeoff between expectation and variance in Markov decision processes

  The stochastic shortest path problem asks to resolve the non-deterministic choices in a Markov decision process (MDP) such that the expected accumulated weight before reaching a target state is maximized. This problem is well-studied and solvable in polynomial time. An optimal strategy might, howeve...

• 2022-11-16, godz. 14:15, 5050

  Mikołaj Bojańczyk (MIM UW)

  Folding interpretations

  In this talk, I will discuss a characterisation of the polyregular functions which uses folding. The idea is to use the combinator approach, i.e. start with certain atomic functions (such as list concatenation) and apply certain combinators (such as function composition). However, we want one of the...

• 2022-11-09, godz. 14:15, 5050

  Paweł Parys (MIM UW)

  Weak Bisimulation Finiteness of Pushdown Systems With Deterministic ε-Transitions Is 2-EXPTIME-Complete

  We consider the problem of deciding whether a given pushdown system all of whose ε-transitions are deterministic is weakly bisimulation finite, that is, whether it is weakly bisimulation equivalent to a finite system. We prove that this problem is 2-EXPTIME-complete. This consists of three elem...

• 2022-10-26, godz. 14:15, 5050

  Michael Blondin (Université de Sherbrooke)

  Separators in continuous Petri nets

  In this talk, we will consider Petri nets: a well-established formalism for the analysis of concurrent systems. Testing whether a target Petri net configuration cannot be reached often amounts to proving the absence of bugs in a system. Thus, formally certifying unreachability is practically (an...

• 2022-10-19, godz. 14:15, 5050

  Szymon Toruńczyk (MIM UW)

  On monadically stable and monadically NIP classes of graphs

  Sparsity theory, initiated by Ossona de Mendez and Nesetril, identifies those classes of sparse graphs that are tractable in various ways (e.g. from the perspective of the model checking problem for first order logic) as exactly the nowhere dense classes. There is an ongoing effort aimed at gene...

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