Lista referatów

• 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...

• 2022-03-02, godz. 14:15, 5050

  Rafał Stefański (MIM UW)

  Single-use automata and transducers—current standpoint

  Register automata (as defined by Kaminski and Francez) are an established tool for studying languages and transductions over infinite alphabets. They share many desired properties of finite automata, but they also miss a few key ones. For example, their definitions are unstable—one-way determinist...

• 2022-01-26, godz. 14:15, Online

  Jan Otop (Instytut Informatyki, Uniwersytet Wrocławski)

  Active learning automata with syntactic queries

  Regular languages can be actively learned with membership and equivalence queries in polynomial time. The learning algorithm, called the L^* algorithm, constructs iteratively the right congruence relation of a given regular language L, and returns the minimal DFA recognizing L. The L^* algorithm has...

• 2022-01-19, godz. 14:15, 5050

  Łukasz Orlikowski (MIM UW)

  Improved Lower Bounds for the Reachability Problem in Fixed Dimensional VASSes

  Complexity of the reachability problem in Vector Addition Systems (VASes) was a long standing problem for a few decades. Despite settling the computational complexity of the reachability problem in VASSes to be Ackermann-complete a lot of questions about VASSes remain to be solved. Even the reachabi...

• 2022-01-12, godz. 14:15, 5050

  Pierre Ohlmann (MIM UW)

  Characterising one-player positionality for infinite duration games on graphs

  I will present a new result, asserting that a winning condition (or, more generally, a valuation) which admits a neutral letter is positional over arbitrary arenas if and only if for all cardinals there exists a universal graph which is monotone and well-founded. Here, "positional" refers only to th...

• 2021-12-22, godz. 14:15, online

  Marcin Przybyłko (University of Bremen)

  Answer Counting and Guarded TGDs

  Answer Counting is simply the problem of counting the number of solutions to a given query. Tuple-Generating Dependencies (TGDs) are a common formalism for formulating database constraints. A TGD states that if certain facts are true, then certain other facts must be true as well. In Ontology-Med...

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