Lista referatów

• 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...

• 2022-10-11, godz. 14:15, 5820

  Stefan Göller (Universität Kassel)

  The AC0-complexity of visibly pushdown languages.

  The talk will be on the question which visibly pushdown languages (VPLs) are in the complexity class AC0. We provide a conjectural characterization that isolates a stubborn subclass of very particular one-turn visibly pushdown languages (that we call intermediate VPLs) any of which our community ...

• 2022-10-05, godz. 14:15, 5050

  Nguyễn Lê Thành Dũng (École normale supérieure de Lyon)

  A transducer model for simply typed λ-definable functions

  Among the natural ways to define functions ℕ^k -> ℕ in the simply typed λ-calculus, one of them allows hyperexponential growth (any tower of exponentials) but excludes many basic functions such as subtraction and equality, as was discovered by Statman in the 1980s. Until now, this function clas...

• 2022-06-15, godz. 14:15, 5050

  Albert Gutowski (MIM UW)

  Finite entailment of UCRPQs over ALC ontologies

  We solve finite ontology-mediated query entailment for ontologies expressed in ALC (a description logic, closely related to (multi)modal logic) and queries expressed as UCRPQs (extending UCQs - unions of conjunctive queries - with constraints on paths given by regular expressions). We combine a sim...

• 2022-06-08, godz. 14:15, 5050

  Jędrzej Kołodziejski (MIM UW)

  Multi-valued Fixpoint Logic

  We investigate multi-valued fixpoint logic, an extension of the classical mu-calculus where logical values range over a fixed complete lattice A equipped with monotone operations as connectives. We present equivalent game semantics for the logic and use it to investigate the case when A is the unit...

• 2022-06-01, godz. 14:15, 5050

  Michał Skrzypczak (MIM UW)

  Computing measures of regular languages via fixpoint expressions

  During the talk I will present our ongoing work with Damian Niwiński and Paweł Parys on computing measures of regular languages. Our approach (following earlier results with Marcin Przybyłko) is to reduce the problem to certain fixpoint expression evaluated in a specific ordered set (called Proba...

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