Organizatorzy

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

Informacje

środy, 14:15 , sala: 5440

Dziedziny badań

Lista referatów

8 listopada 2023 14:15
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, …
25 października 2023 14:15
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, …
18 października 2023 14:15
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 …
11 października 2023 14:15
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 …
4 października 2023 14:15
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 …
6 września 2023 14:15
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 …
5 lipca 2023 14:15
Michał Gajda (MigaMake Pte Ltd, Singapur)
Semigroup decomposition and semigroup transformers
Krohn-Rhodes theorem claims that every semigroup can be decomposed into finite groups, and aperiodic semigroups. This theorem has been generalized from finite semigroups to infinite ones, but uses a hairy construct of a wreath product, …
21 czerwca 2023 14:15
Damian Niwiński (MIM UW)
On the complexity of conditional independence
A conditional independence statement says that, for example, random variables (X,Y) and (W,Y,Z) are independent given a random variable (U,V). Cheuk Ting Li showed in 2022 that it is undecidable if a Boolean combination of …
14 czerwca 2023 14:15
Nathanaël Fijalkow (CNRS, LaBRI, University of Bordeaux & MIM UW)
Sampling and enumerating for probabilistic context-free grammars
I'll discuss algorithms for sampling and enumerating terms from a given probabilistic context-free grammar. It will be mostly a "Not my theorem" session, with early contributions from back in 1974, but if time permits I'll …
7 czerwca 2023 14:15
Pierre Ohlmann (MIM UW)
Finite versus infinite arenas for positionality in infinite duration games
This talk is about positionality (for the protagonist) in infinite duration games, either over finite or over arbitrary arenas. The aim is to compare the two notions. Classically, it is well known that the parity …
31 maja 2023 14:15
Szymon Toruńczyk (MIM UW)
Flip-width
I will define a new graph parameter called flip-width. Graph classes of bounded flip-width include classes of bounded expansion of Nesetril and Ossona de Mendez, as well as classes of bounded twin-width of Bonnet, Kim, …
24 maja 2023 14:15
Mikołaj Bojańczyk (MIM UW)
A categorical characterisation of linear regular functions
We consider linear regular string-to-string functions, i.e. functions that are recognized by copyless streaming string transducers, or any of their equivalent models, such as deterministic two-way automata. Although this class of functions is clearly important, …
17 maja 2023 14:15
Liat Peterfreund (CNRS, LIGM, Paris-Est University)
Querying incomplete numerical data: between certain and possible answers
Queries with aggregation and arithmetic operations, as well as incomplete data, are common in real-world databases, but we lack a good understanding of how they should interact. On the one hand, systems based on SQL …
10 maja 2023 14:15
Nikolas Mählmann (University of Bremen)
Monadically Stable Classes of Graphs
Intuitively, a class of graphs is monadically stable if first-order logic cannot encode arbitrary long linear orders in it. While originating from model theory, monadic stability generalizes many combinatorial properties of sparse graph classes such …
26 kwietnia 2023 14:15
Yoàv Montacute (University of Cambridge)
Logic and Dynamical Systems
The study of the relationship between logic and topology has a rich and extensive history. One way of exploring this relationship involves examining the formal languages of indiscrete spaces and their discrete representations. The talk …