Organizers

prof. dr hab. Mikołaj Bojańczyk
prof. dr hab. Damian Niwiński

Information

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

Research fields

List of talks

May 20, 2020, 2:15 p.m.
Vincent Michielini (Uniwersytet Warszawski)
joint work with Michał Skrzypczak
Considering the following question: given (in a sense which will be clarified in the talk) a countable totally ordered set D, on which condition(s) does there exist a choice function over D (i.e. a function …
May 13, 2020, 2:15 p.m.
Denis Kuperberg (CNRS, LIP, ENS Lyon)
joint work with Laureline Pinault and Damien Pous
Cyclic proofs are a class of formal proof systems that allow some kind of circular reasoning. Unlike classical proofs, represented by finite trees with axioms as leaves, cyclic proofs are represented by trees containing infinite …
May 6, 2020, 2:15 p.m.
Filip Mazowiecki (MPI SWS)
joint work with Alejandro Grez, Michał Pilipczuk, Gabriele Puppis and Cristian Riveros
We study a variant of the classical membership problem in automata theory, which consists of deciding whether a given input word is accepted by a given automaton. We do so under a different perspective, that …
April 29, 2020, 2:15 p.m.
Mikołaj Bojańczyk (Uniwersytet Warszawski)
joint work with Rafał Stefański
Automata for infinite alphabets, despite the undeniable appeal, are a bit of a theoretical mess. Almost all models are non-equivalent as language recognisers: deterministic/nondeterministic/alternating, one-way/two-way, etc. Also monoids give a different class of languages, and …
April 22, 2020, 2:15 p.m.
Wojciech Czerwiński (Uniwersytet Warszawski)
joint work with Diego Figueira and Piotr Hofman
I will show that the universality problem is ExpSpace-complete for unambiguous VASS, which is in strong contrast with Ackermann-completeness of the same problem for nondeterministic VASS. I also plan to present some more results concerning …
April 15, 2020, 2:15 p.m.
Bartek Klin (Uniwersytet Warszawski)
Monadic MSO logic
The correspondence of regular languages and monadic second-order logic relies on the fact that the class of regular languages is closed under images of surjective letter-to-letter homomorphisms. This closure property holds for finite words, but …
April 8, 2020, 2:15 p.m.
David Barozzini (Uniwersytet Warszawski)
Higher-order recursion schemes are an expressive formalism used to define languages of possibly infinite ranked trees.
Higher-order recursion schemes are an expressive formalism used to define languages of possibly infinite ranked trees. We prove, under a syntactical constraint called safety, decidability of the model-checking problem for recursion schemes against properties defined …
April 1, 2020, 2:15 p.m.
Engel Lefaucheux (MPI SWS)
Monniaux Problem in Abstract Interpretation
The Monniaux Problem in abstract interpretation asks, roughly speaking, whether the following question is decidable: given a program P, a safety specification φ, and an abstract domain of invariants D, does there exist an inductive …
March 25, 2020, 2:15 p.m.
Radosław Piórkowski (Uniwersytet Warszawski)
Online seminar) Timed games and deterministic separability
The presentation is based on my recent joint work with Lorenzo Clemente and Sławomir Lasota. We study a generalisation of Büchi-Landweber games to the timed setting, where Player I plays timed actions and Player II …
March 18, 2020, 2:15 p.m.
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No seminar
March 11, 2020, 2:15 p.m.
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No seminar
March 4, 2020, 2:15 p.m.
Gaëtan Douéneau-Tabot (ENS Paris-Saclay)
Optimisation of simple programs using pebble and marble transducers
Several models of automata with outputs (known as transducers) have been defined over the years to describe various classes of “regular-like” functions. Such classes generally have good decidability properties, and they have been shown especially …
Feb. 26, 2020, 2:15 p.m.
Mikołaj Bojańczyk (Uniwersytet Warszawski)
joint work with Amina Doumane
We study tree-to-tree transformations that can be defined in logics such as first-order logic or monadic second-order logic.We show that such transformations can be decomposed into certain primitive transformations, such as tree-to-tree homomorphisms or pre-order traversal, by using combinators such …
Feb. 5, 2020, 2:15 p.m.
Nathan Lhote (Uniwersytet Warszawski)
Pebble minimization for polyregular functions
We show that a polyregular word-to-word function is regular if and only its output size is at most linear in its input size. Moreover a polyregular function can be realized by: a transducer with …
Jan. 29, 2020, 2:15 p.m.
Piotr Hofman (Uniwersytet Warszawski)
joint work with Jakub Różycki
Consider a Petri net in which every token carries a k-element set of data, and whenever we fire a transition then data from consumed and produced tokens are compared for equality and disequality. Such an …