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

Nov. 13, 2024, 2:15 p.m.
Szymon Toruńczyk (University of Warsaw)
Mergewidth and FirstOrder Model Checking (Mergewidth and FirstOrder Model Checking)
We introduce mergewidth, a family of graph parameters that unifies several structural graph measures, including treewidth, degeneracy, twinwidth, cliquewidth, and generalized coloring numbers. Graph classes of bounded mergewidth – for which the radiusr mergewidth parameter …

Nov. 6, 2024, 2:15 p.m.
Mathieu Lehaut (University of Gothenburg)
Synthesis for first order specifications over data words (Synthesis for first order specifications over data words)
We study the reactive synthesis problem for distributed systems with a finite but unbounded number of participants interacting with an uncontrollable environment. Executions of those systems are modelled by data words, and specifications are given …

Oct. 30, 2024, 2:15 p.m.
Piotr Hofman (University of Warsaw)
Soundness for Workflows with Reset Arcs (Soundness for Workflows with Reset Arcs)
Workflows are a subclass of Petri nets designed to model business processes. Various definitions of soundness for workflows have been proposed, with the two most prominent being "soundness" and the stronger "generalized soundness." We begin …

Oct. 23, 2024, 2:15 p.m.
Antoni Puch (University of Warsaw)
Minimising ambiguity of weighted automata (Minimising ambiguity of weighted automata)
By bounding the number of accepting runs of automata we obtain various subclasses of them. We consider: unambiguous automata, finitelyambiguous automata, and polynomiallyambiguous automata, where the number of runs is bounded by 1, a constant, …

Oct. 16, 2024, 2:15 p.m.
Antonio Casares (University of Warsaw)
An algorithm to rule them all: Fast value iteration for energy games (An algorithm to rule them all: Fast value iteration for energy games)
We introduce a uniform framework for describing, comparing, and proving correctness of algorithms for energy games (which generalise the well known parity games). This framework allows us to provide simple presentations and correctness proofs of …

Oct. 9, 2024, 2:15 p.m.
Lorenzo Clemente (University of Warsaw)
Control theory and series in noncommuting variables (Control theory and series in noncommuting variables)
We present Michel Fliess' work from the 1970's showing surprising connections between control theory and the theory of series in noncommuting variables. More precisely, to a dynamical system with inputs S one can associate a …

Oct. 2, 2024, 2:15 p.m.
Ioannis Eleftheriadis (University of Cambridge)
Preservation theorems on tame classes of finite structures (Preservation theorems on tame classes of finite structures)
Preservation theorems provide a correspondence between the syntactic structure and the semantic behaviour of firstorder sentences. The study of preservation theorems relativised to classes of finite structures was initiated by Atserias, Dawar, and Kolaitis [JACM, …

Sept. 4, 2024, 2:15 p.m.
Sven Manthe (University of Bonn)
The Borel monadic theory of order is decidable (The Borel monadic theory of order is decidable)
When proving decidability of S2S, Rabin derived decidability of the monadic theory of (ℝ,<) with quantification restricted to Fσsets. Undecidability of the unrestricted monadic theory of (ℝ,<) was proven by Shelah. We discuss decidability for …

June 19, 2024, 2:15 p.m.
Teodor Knapik (ISEA, Université de la Nouvelle Calédonie)
Lindenmayer graph languages, firstorder theories and expanders (Lindenmayer graph languages, firstorder theories and expanders)
Imagined by Kolmogorov in the middle of past century, expanders form remarkable graph families with applications in areas as diverse as robust communication networks and probabilistically checkable proofs, to name just two. Since the proof …

June 12, 2024, 2:15 p.m.
Łukasz Kamiński (University of Warsaw)
Bireachability in Petri nets with data
Petri nets with equality data is an extension of plain Petri nets where tokens carry values from an infinite data domain, and executability of transitions is conditioned by equalities between data values. The most fundamental …

June 5, 2024, 2:15 p.m.
Vincent Michielini (University of Warsaw)
A new characterisation for FO2 over finite words
FirstOrder Logic with two variables, over finite words, is known for having many semantic characterisations: turtle languages, unambiguous monomials, deterministic partially ordered 2way automata... In this talk, we will focus on the second one: a …

May 29, 2024, 2:15 p.m.
Filip Mazowiecki (University of Warsaw)
Determinisation and Unambiguisation of PolynomiallyAmbiguous Rational Weighted Automata
We study the determinisation and unambiguisation problems of weighted automata over the rational field: given a weighted automaton, can we determine whether there exists an equivalent deterministic, respectively unambiguous, weighted automaton? Recent results by Bell …

May 22, 2024, 2:15 p.m.
Jakub Kozik (Jagiellonian University)
Choosability version of Thue's theorem on nonrepetitive sequences
Pattern avoidance is a deeply studied problem within the field of combinatorics on words. One of the seminal results of this area is the theorem of Thue which asserts that there exists an infinite word …

May 15, 2024, 2:15 p.m.
Igor Walukiewicz (CNRS, LaBRI, Bordeaux University)
Rethinking PartialOrder Methods
The goal of partialorder methods is to speed up explicit state exploration of concurrent systems. The state space of these systems grows exponentially with the number of components. Yet, explicit state exploration remains one of …

April 24, 2024, 2:15 p.m.
Gorav Jindal (Max Planck Institute for Software Systems)
Sign Me Up: PosSLP, Sign Testing, and Polynomials
Given an integer, deciding its positivity may appear trivial initially. However, this problem becomes more compelling when the integer is presented in a compact form, as opposed to being explicitly represented as a bit string. …