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Seminar Automata Theory

Weekly research seminar


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

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List of talks

  • 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
    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 …

  • March 6, 2024, 2:15 p.m.
    Szymon Toruńczyk (MIMUW)
    Combinatorial Characterizations of Monadically Dependent Graph Classes
    We provide the first two combinatorial characterizations of monadically dependent graph classes. This yields the following dichotomy. On the structure side, we characterize monadic dependence by a property called flip-breakability. This notion generalizes the notions …

  • Feb. 28, 2024, 2:15 p.m.
    Michał Pilipczuk (MIMUW)
    First-Order Model Checking on Monadically Stable Graph Classes
    A graph class C is monadically stable if one cannot interpret arbitrary long linear orders in colored graphs from C using any fixed first-order interpretation. We prove that on any monadically stable class, the model-checking …

  • 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 …