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Cotygodniowe seminarium badawcze
2022-03-02, godz. 14:15, 5050
Rafał Stefański (MIM UW)
Single-use automata and transducers—current standpoint
Register automata (as defined by Kaminski and Francez) are an established tool for studying languages and transductions over infinite alphabets. They share many desired properties of finite automata, but they also miss a few key ones. For example, their definitions are unstable—one-way determinist...
2022-01-26, godz. 14:15, Online
Jan Otop (Instytut Informatyki, Uniwersytet Wrocławski)
Active learning automata with syntactic queries
Regular languages can be actively learned with membership and equivalence queries in polynomial time. The learning algorithm, called the L^* algorithm, constructs iteratively the right congruence relation of a given regular language L, and returns the minimal DFA recognizing L. The L^* algorithm has...
2022-01-19, godz. 14:15, 5050
Łukasz Orlikowski (MIM UW)
Improved Lower Bounds for the Reachability Problem in Fixed Dimensional VASSes
Complexity of the reachability problem in Vector Addition Systems (VASes) was a long standing problem for a few decades. Despite settling the computational complexity of the reachability problem in VASSes to be Ackermann-complete a lot of questions about VASSes remain to be solved. Even the reachabi...
2022-01-12, godz. 14:15, 5050
Pierre Ohlmann (MIM UW)
Characterising one-player positionality for infinite duration games on graphs
I will present a new result, asserting that a winning condition (or, more generally, a valuation) which admits a neutral letter is positional over arbitrary arenas if and only if for all cardinals there exists a universal graph which is monotone and well-founded. Here, "positional" refers only to th...
2021-12-22, godz. 14:15, online
Marcin Przybyłko (University of Bremen)
Answer Counting and Guarded TGDs
Answer Counting is simply the problem of counting the number of solutions to a given query. Tuple-Generating Dependencies (TGDs) are a common formalism for formulating database constraints. A TGD states that if certain facts are true, then certain other facts must be true as well. In Ontology-Med...
2021-12-15, godz. 14:15, online
Filip Mazowiecki (Max Planck Institute for Software Systems)
The boundedness and zero isolation problems for weighted automata over nonnegative rationals
We consider linear cost-register automata (equivalently, weighted automata) over the semiring of nonnegative rationals, which generalise probabilistic automata. The two problems boundedness and zero isolation ask whether there is a sequence of words that converge to infinity and zero, respectively. ...
2021-12-08, godz. 14:15, Online
Arka Ghosh (MIM UW)
Orbit-finite System of Linear Equations (Joint work with P.Hofman and S.Lasota)
An orbit-finite system of linear equations is a system of linear equations where the equations and the variables used in them are possibly infinite but are finite up to certain symmetries. I will start with a brief description of atoms and orbit-finite sets. Then I will define vector spaces over orb...
2021-12-01, godz. 14:15, online
Ismaël Jecker (MIM UW)
A finite automaton A is called composite if there exist automata A1, A2, . . . , Ak smaller than A such that the language of A is equal to the intersection of the languages of the Ai. Otherwise, A is prime. This notion of primality was introduced by Orna Kupferman and Jonathan Mosheiff in 2015, but...
2021-11-24, godz. 14:15, online
Krzysztof Ziemiański (MIM UW)
Higher dimensional automata (HDA) are a formalism for modeling concurrent systems introduced by Pratt and van Glabbeek. I will present several ways to define languages of HDA, which are collections of interval pomsets closed under subsumption. Then I will define regular interval pomset languages and...
2021-11-17, godz. 14:15, 5050
Jędrzej Kołodziejski (MIM UW)
Taming (un)boundedness - logic, automata and games with countdown
I will present extensions of: the modal fixpoint calculus, parity games, and parity automata - designed to capture (un)boundedness-related phenomena. The extensions lift the classical logic~games~automata correspondence beyond regular properties - in particular the logic and automata define the same...
