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Weekly research seminar
Organizers
- prof. dr hab. Mikołaj Bojańczyk
- prof. dr hab. Damian Niwiński
Information
Wednesdays, 2:15 p.m. , room: 5440Research fields
List of talks
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April 23, 2025, 2:15 p.m.
Mathieu Lehaut (University of Warsaw)
Asynchronous automata, trees, and reconfigurability (Asynchronous automata, trees, and reconfigurability)
I will present some results about Zielonka's asynchronous automata, which are a popular automata model for concurrent programs. Zielonka's seminal result about distributivity shows that one can go from a centralized specification given by a …
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April 16, 2025, 2:15 p.m.
Henry Sinclair-Banks (University of Warsaw)
Reaching Semilinear Target Sets in Automata with One Counter (Reaching Semilinear Target Sets in Automata with One Counter)
I will introduce a (novel) generalised reachability problem in automata with one counter with a variety of semantics. The goal of the seminar is to identify what features of target sets make the reachability problem …
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April 9, 2025, 2:15 p.m.
Aliaume Lopez (University of Warsaw)
Well-quasi-ordered classes of graphs and bounded linear clique-width (Well-quasi-ordered classes of graphs and bounded linear clique-width)
A quasi-ordered set (X, ≤) is a well-quasi-order (WQO) whenever it contains neither infinite antichains, nor infinite decreasing sequences. A cornerstone result of structural graph theory is the Graph Minor Theorem of Robertson and Seymour, …
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April 2, 2025, 2:15 p.m.
Jakub Gajarský (University of Warsaw)
3D-grids are not transducible from planar graphs (3D-grids are not transducible from planar graphs)
We prove that the class of 3D-grids cannot be obtained by a first-order transduction from the class of planar graphs, and more generally, from any class of graphs of bounded genus. This is a part …
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March 26, 2025, 2:15 p.m.
Francesco Dolce (Czech Technical University in Prague)
A gentle introduction to bifix codes and dendric languages (A gentle introduction to bifix codes and dendric languages)
A code is a set of words over an alphabet which can be uniquely decoded when concatenated. It is a bifix code if none of its elements is a prefix or a suffix of another …
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March 19, 2025, 2:15 p.m.
Michał Skrzypczak (University of Warsaw)
Generalised Quantifiers Based on Rabin-Mostowski Index (Generalised Quantifiers Based on Rabin-Mostowski Index)
I will present our novel results obtained with Denis Kuperberg, Damian Niwiński, and Paweł Parys. The framework is Monadic Second-Order (MSO) logic over \omega-words and infinite trees. We begin with the index problem, which asks, …
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March 12, 2025, 2:15 p.m.
Wojciech Przybyszewski (University of Warsaw)
Flipping and forking (Flipping and forking)
In model theory, a model is called stable if it does not encode arbitrarily long linear orders using a single fixed formula, ensuring a form of combinatorial tameness. Stability is a central concept in Shelah’s …
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March 5, 2025, 2:15 p.m.
Vincent Michielini (University of Warsaw)
Query Entailment Problem for S (Query Entailment Problem for S)
In description logic, possibly infinite structures are described via an ABox A (i.e. a basic finite structure, to be completed), and an ontology T (or a TBox, a finite set of constraints aiming to complete …
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Feb. 26, 2025, 2:15 p.m.
Karolina Drabik (University of Warsaw)
Fined-Grained Complexity of Ambiguity Problems on Automata and Directed Graphs (Fined-Grained Complexity of Ambiguity Problems on Automata and Directed Graphs)
Two fundamental classes of finite automata are deterministic and nondeterministic ones (DFAs and NFAs). Natural intermediate classes arise from bounds on an NFA's allowed ambiguity, i.e. number of accepting runs per word: unambiguous, finitely ambiguous, …
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Feb. 19, 2025, 2:15 p.m.
Rafał Stefański (University of Warsaw)
Polyregular model checking (Polyregular model checking)
We reduce the model checking problem for a subset of Python to the satisfiability of a first-order formula over finite words, which is known to be decidable. The reduction is based on the theory of …
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Feb. 5, 2025, 2:15 p.m.
Wojciech Czerwiński (University of Warsaw)
Reachability in 3-VASS is Elementary (Reachability in 3-VASS is Elementary)
I will present our recent result (with Ismael Jecker, Sławomir Lasota and Łukasz Orlikowski) about the reachability problem in 3-dimensional Vector Addition Systems with States (VASS). We have shown that the problem is in 2-ExpSpace, …
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Jan. 29, 2025, 2:15 p.m.
Andrew Ryzhikov (University of Warsaw)
A guide to tax-free travelling between codes, automata and matrices (A guide to tax-free travelling between codes, automata and matrices)
In this tutorial talk, I will describe a tight and fruitful relationship between variable-length codes (bases of free submonoids of a free monoid), unambiguous finite automata and semigroups of zero-one matrices. I will concentrate on …
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Jan. 22, 2025, 2:15 p.m.
Giannos Stamoulis (University of Warsaw)
Low rank MSO (Low rank MSO)
We introduce a new logic for describing properties of graphs, which is called low rank MSO. This is the fragment of monadic second-order logic (MSO), in which set quantification is restricted to sets of bounded …
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Jan. 15, 2025, 2:15 p.m.
Mikołaj Bojańczyk (University of Warsaw)
Graphs of unbounded linear cliquewidth. (Graphs of unbounded linear cliquewidth.)
We show that for every class C of graphs, one of the following holds: 1. The class has bounded linear cliquewidth; or 2. There is a surjective MSO transduction from C to the class of …
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Dec. 18, 2024, 2:15 p.m.
Lorenzo Clemente (University of Warsaw)
The commutativity problem for varieties of formal series and applications (The commutativity problem for varieties of formal series and applications)
Let Σ be a finite alphabet of noncommuting indeterminates. A *formal series* over the rational numbers is a mapping Σ* → ℚ. We say that it is *commutative* if the output does not depend on …
