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Seminar Automata Theory

Weekly research seminar


Organizers

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Wednesdays, 2:15 p.m. , room: 5440

Research fields

List of talks

  • 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 first-order 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 Fσ-sets. 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, first-order theories and expanders (Lindenmayer graph languages, first-order 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)
    Bi-reachability 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
    First-Order Logic with two variables, over finite words, is known for having many semantic characterisations: turtle languages, unambiguous monomials, deterministic partially ordered 2-way 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 Polynomially-Ambiguous 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 Partial-Order Methods
    The goal of partial-order 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. …

  • April 17, 2024, 2:15 p.m.
    Shuo Pang (University of Copenhagen)
    Supercritical and Robust Trade-offs for Resolution Depth Versus Width and Weisfeiler–Leman
    We give the first robust resolution trade-offs for which low width implies depth superlinear in the formula size. We show analogous results for the Weisfeiler–Leman algorithm, which also translate into trade-offs between number of variables …

  • April 10, 2024, 2:15 p.m.
    Clotilde Biziere (University of Warsaw / ENS Paris)
    Reachability in 2-dimensional Branching Vector Addition Systems with States
    Vector addition systems with states (VASS) are finite-state machines equipped with a finite number of counters ranging over nonnegative integers. Operations on counters are limited to incrementation and decrementation. Their central algorithmic problem is reachability: …

  • April 3, 2024, 2:15 p.m.
    Tomasz Gogacz (University of Warsaw)
    TBA
    TBA

  • March 27, 2024, 2:15 p.m.
    Tim Seppelt (RWTH Aachen University)
    Homomorphism Indistinguishability: Characterisations, Closure, Complexity
    In 1967, Lovász proved that two graphs G and H are isomorphic iff they are homomorphism indistinguishable over the the family of all graphs, i.e. for all graphs F the number of homomorphisms from F …

  • March 20, 2024, 2:15 p.m.
    Jingjie Yang (University of Oxford)
    Equivariant subspaces of orbit-finite-dimensional vector spaces (Niezmiennicze podprzestrzenie przestrzeni liniowych orbitowo skończonego wymiaru)
    In their LICS21 paper, Bojańczyk, Klin, and Moerman gave an equivalence algorithm for weighted orbit-finite automata: they construct a chain of configuration spaces that are closed under both linear combinations and atom permutations; crucially, termination …

  • March 13, 2024, 2:15 p.m.
    Alexandra Rogova
    Connecting graph and relational query languages
    Practical query languages for graph and relational databases are based on similar concepts: In the former, base relations are extracted from graphs, and in the latter, they are given as input. In both, these base …