Lista referatów

• 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...

• 2022-04-06, godz. 14:15, 5050

  Rose McCarty (MIM UW)

  Vertex-minors: dense graphs from sparse graphs

  Structural graph theory has traditionally focused on graph classes that are sparse (that is, only contain graphs with few edges). Lately, however, there has been an ongoing shift towards the dense setting. In the first half of the talk we discuss how vertex-minors fit into this paradigm. In the seco...

• 2022-03-23, godz. 14:15, 5050

  Marcin Jurdziński (University of Warwick)

  Attractor decompositions and their applications in games and automata

  An attractor decomposition is a natural inductively defined decomposition of a graph that satisfies the parity condition, and its “shape” can be described by an ordered tree. The McNaughton-Zielonka algorithm implicitly produces an attractor decomposition of the winning set in a parity game. W...

• 2022-03-16, godz. 14:15, 5050

  Michał Pilipczuk (MIM UW)

  Dimension of posets of bounded cliquewidth

  Dimension and boolean dimension are two structural measures for posets (partially ordered sets). Roughly speaking, they measure the minimum number of linear orders sufficient for encoding the poset. We will discuss a proof that posets of bounded cliquewidth have bounded boolean dimension and are dim...

• 2022-03-09, godz. 14:15, Online

  Marie Fortin (University of Liverpool)

  How undecidable are HyperLTL and HyperCTL*?

  Temporal logics for the specification of information-flow properties are able to express relations between multiple executions of a system. Two of the most important such logics are HyperLTL and HyperCTL*, which generalise LTL and CTL* by trace quantification. It is known that this expressiveness co...

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