Lista referatów

• 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...

• 2022-05-25, godz. 14:15, 5050

  Olivier Carton; Sebastian Maneth (University of Paris; University of Bremen)

  Tight links between normality and automata; Two Applications of the Parikh Property

  Abstract (Tight links between normality and automata): Normality has been introduced by É. Borel more than one hundred years ago. A real number is normal to an integer base if, in its infinite expansion expressed in that base, all blocks of digits of the same length have the same limiting frequenc...

• 2022-05-11, godz. 14:15, 5050

  Filip Mazowiecki (MIM UW)

  The complexity of soundness in workflow nets

  Workflow nets are a popular variant of Petri nets that allow for algorithmic formal analysis of business processes. The central decision problems concerning workflow nets deal with soundness, where the initial and final configurations are specified. Intuitively, soundness states that from every reac...

• 2022-04-27, godz. 14:15, 5050

  David Purser (MIM UW)

  The Skolem Problem for Simple Linear Recurrence Sequences

  The Skolem Problem, asks to decide whether a linear recurrence sequence has a zero term. The Skolem-Mahler-Lech theorem states that the set of zeros of a linear recurrence sequence is the union of a finite set and finitely many arithmetic progressions. Although the result is almost 90 years old, the...

• 2022-04-20, godz. 14:15, 5050

  Wojciech Przybyszewski (MIM UW)

  Definability of neighborhoods in graphs of bounded twin-width and its consequences

  During the talk, we will study set systems formed by neighborhoods in graphs of bounded twin-width. In particular, we will show how, for a given graph from a class of graphs of bounded twin-width, to efficiently encode the neighborhood of a vertex in a given set of vertices A of the graph. For the e...

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