Organizatorzy

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

Informacje

środy, 14:15 , sala: 5440

Dziedziny badań

Lista referatów

3 czerwca 2015 14:15
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There is no seminar this week
27 maja 2015 14:15
Leszek Kołodziejczyk (Uniwersytet Warszawski)
How unprovable is Rabin's theorem?
Second-order arithmetic is an axiomatic theory in a language with two sorts of variables, one for representing natural numbers and the other for representing sets of natural numbers. The theory is roughly as strong as …
20 maja 2015 14:15
Michael Blondin (ENS Cachan and Université de Montréal)
Reachability in Two-Dimensional Vector Addition Systems with States (joint work with Alain Finkel, Stefan Göller, Christoph Haase and Pierre McKenzie)
Known to be decidable since 1981, there still remains a huge gapbetween the best known lower and upper bounds for the reachabilityproblem for vector addition systems with states (VASS). In this talk,the reachability problem is …
13 maja 2015 14:15
Filip Mazowiecki (Uniwersytet Warszawski)
On the expressibility of copyless cost register automata (joint work with Cristian Riveros)
Cost register automata (CRA) and its subclass, copyless CRA, were recently proposed as a new computational model. We study the properties and expressiveness of the copyless CRA. Our studies lead to results that copyless CRA …
6 maja 2015 14:15
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There is no seminar this week
29 kwietnia 2015 14:15
Adam Witkowski (Uniwersytet Warszawski)
Solving datalog containment via bounded cliquewidth
Containment of monadic datalog over data trees is known to be undecidable in general but decidablefor two fragments: downward programs and linear child-only ones.I will describe a method for deciding the containment by bounding clique-width …
22 kwietnia 2015 14:15
Joost Winter (Uniwersytet Warszawski)
Coinductive stream calculus
In this talk, I will give an introduction to the coinductive stream calculus (developed by Rutten, McIlroy, and others), its connection to coalgebra, automata theory and implementations in the functional programming language Haskell. We take …
15 kwietnia 2015 14:15
Das Anupam (École Normale Supérieure de Lyon)
A Complete Axiomatization of MSO on Infinite Trees
We show that an adaptation of Peano’s axioms for second-orderarithmetic to the language of MSO completely axiomatizes the theoryover infinite trees. This continues a line of work begun by Büchiand Siefkes with axiomatizations of MSO …
8 kwietnia 2015 14:15
Charles Paperman (Uniwersytet Warszawski)
Regular languages of AC_0
I will present a full proof of the theorem of Barington, Compton, Straubing and Therien characterizing regular languages of AC_0 based on a recent algebraic techniques.
1 kwietnia 2015 14:15
Eryk Kopczyński (Uniwersytet Warszawski)
Spectra and variables
Given a formula \phi of some logic, the spectrum of \phi, denoted spec(\phi), is the set of non-negative integers n such that \phi has a model of cardinality n. The notion of a spectrum has …
25 marca 2015 14:15
Mikołaj Bojańczyk (Uniwersytet Warszawski)
The MSO+U theory of (N, <) is undecidable)
We consider the logic MSO+U, which is monadic second-order logic extended with the unbounding quantifier. The unbounding quantifier is used to say that a property of finite sets holds for sets of arbitrarily large size. …
18 marca 2015 14:15
Amaldev Manuel (Uniwersytet Warszawski)
Mu-calculus on data words (joint work with Thomas Colcombet)
I will describe Data automata, FO^2 and some natural fragments of Data automata defined by classes of Mu-calculus formulas and wrap it up by separating two classes using the circuits we discussed last time. If …
11 marca 2015 14:15
Charles Paperman (Uniwersytet Warszawski)
Circuits complexity and regular languages
I will talk about classical and recent developments on the subject: "Deciding the membership of regular languages in circuits complexity classes". This question is deeply interwoven with the algebraic characterization of classes of regular languages …
4 marca 2015 14:15
Henryk Michalewski (Uniwersytet Warszawski)
From parity games to linear optimization and back
Linear programs (LPs) can be solved efficiently, hence thedesire to reduce the parity games (PGs) to LPs. This seminar will bedevoted to a summary of attempted reductions published over the last 20 years.A polynomial solution …
25 lutego 2015 14:15
Wojciech Czerwiński (Uniwersytet Warszawski)
Tree Pattern Minimisation (joint work with Wim Martens, Matthias Niewerth and Paweł Parys)
I will consider the problem of minimising tree pattern queries. I will show you the example, which contradicted the long standing conjecture that minimality is the same as nonredundancy. Then I will present how this …