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Seminar Automata Theory

Weekly research seminar



Wednesdays, 2:15 p.m. , room: 5050

Research fields

List of talks

  • Feb. 21, 2024, 2:15 p.m.
    Vincent Michielini (University of Warsaw)
    Complexity of Maslov's Class K-bar
    Maslov’s class K-bar is a fragment of First-Order Logic consisting of formulae in NNF whose variables occurring in the different atoms obey a certain pattern [*]. It embeds many well-known fragments, such as the two-variable …

  • Feb. 14, 2024, 2:15 p.m.
    Daniel Smertnig (University of Ljubljana)
    On the linear hull of a weighted automaton
    Previous work reduces the problem of deciding whether a weighted finite automaton (WFA) over a field is equivalent to a deterministic, respectively, unambiguous, WFA to the computation of the linear hull. The linear hull is …

  • Feb. 7, 2024, 2:15 p.m.
    Mikołaj Bojańczyk (University of Warsaw)
    On function spaces for orbit-finite sets
    Joint work with Tito Nguyen and Rafał Stefański. Orbit-finite sets are a generalisation of finite sets, and as such support many operations allowed for finite sets, such as pairing, quotienting, or taking subsets. However, they …

  • Jan. 31, 2024, 2:15 p.m.
    Cristian Riveros Jaeger (Pontificia Universidad Católica de Chile (PUC Chile))
    #NFA admits an FPRAS
    #NFA is the following problem over non-deterministic finite automata (NFA) over words: you receive as input an NFA A and a length N (in unary), and you want to count the number of words of …

  • Dec. 20, 2023, 2:15 p.m.
    Julie Parreaux (University of Warsaw)
    Playing stochastically in Weighted Timed Games to Emulate Memory
    Weighted timed games are two-player zero-sum games played in a timed automaton equipped with integer weights. We consider optimal reachability objectives, in which one of the players, that we call Min, wants to reach a …

  • Dec. 13, 2023, 2:15 p.m.
    Lorenzo Clemente (University of Warsaw)
    Zeroness of weighted basic parallel processes and other finitely generated classes of series
    We consider a weighted model of computation generalising weighted finite automata over fields, namely weighted basic parallel processes (WBPP). The underlying unweighted BPP model, popular in process algebra, was introduced by Christensen in his PhD …

  • Dec. 6, 2023, 2:15 p.m.
    Antonio Casares (University of Warsaw)
    A characterization of half-positionality for omega-regular languages
    In the context of infinite duration games over graphs, a central question is: For which objectives can the existential player always play optimally using positional (memoryless) strategies? In this talk, we characterize omega-regular objectives with …

  • Nov. 29, 2023, 2:15 p.m.
    Ruiwen Dong (Saarland University)
    Decidability problems in infinite semigroups
    This talk is about several algorithmic problems for matrix semigroups. A classic problem in this area is the well-known Semigroup Membership problem: given as input a finite set of square matrices S = {A1, A2, …

  • Nov. 22, 2023, 2:15 p.m.
    Rafał Stefański (University of Warsaw)
    Recognisable transducers over monads and comonads
    In 2015, Bojańczyk introduced a class of recognizable languages over monads, which is a common generalization of regular languages for many different types of objects, including words, infinite words, and trees. In this talk, I …

  • Nov. 8, 2023, 2:15 p.m.
    Michał Przybyłek (Polish-Japanese Academy of Information Technology)
    Some remarks on Stone-Čech compactification in ZFA
    Working in Zermelo-Fraenkel Set Theory with Atoms over an \omega-categorical \omega-stable structure, we show how some infinite constructions over definable sets can be encoded as finite constructions over Stone-Čech compactification of the sets. In particular, …

  • Oct. 25, 2023, 2:15 p.m.
    Arka Ghosh (University of Warsaw)
    Equivariant polynomial ideals
    In this joint work with Sławek Lasota we study ideals of polynomials, where variables are elements of a countable logical structure. In this setting we allow structure-preserving embeddings to act on polynomials by renaming variables, …

  • Oct. 18, 2023, 2:15 p.m.
    Aliaume Lopez (University of Warsaw)
    From Local to Global Relativization of the Łoś–Tarski Theorem
    We consider first order sentences over a finite relational signature σ. Classical preservation theorems, dating back to the 1950s, state the correspondence between syntactic fragments of FO[σ], and semantic ones. The archetypal example of such …

  • Oct. 11, 2023, 2:15 p.m.
    Mikołaj Bojańczyk (University of Warsaw)
    Polyregular functions on unordered trees of bounded height
    Joint work with Bartek Klin (University of Oxford) We consider first-order interpretations that input and output trees of bounded height. The corresponding functions have polynomial output size, since a first-order interpretation can use a $k$-tuple …

  • Oct. 4, 2023, 2:15 p.m.
    Filip Mazowiecki (University of Warsaw)
    Coverability in VASS Revisited: Improving Rackoff’s Bound to Obtain Conditional Optimality
    Seminal results establish that the coverability problem for Vector Addition Systems with States (VASS) is in EXPSPACE (Rackoff, '78) and is EXPSPACE-hard already under unary encodings (Lipton, '76). More precisely, Rosier and Yen later utilise …

  • Sept. 6, 2023, 2:15 p.m.
    Uli Fahrenberg ( EPITA Rennes & Paris)
    Higher-dimensional automata theory
    I will give a gentle introduction to higher-dimensional automata (HDAs) and their language theory. HDAs have been introduced some 30 years ago as a model for non-interleaving concurrency which generalizes, for example, Petri nets while …