Organizers

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

Information

Wednesdays, 2:15 p.m. , room: 5440

Research fields

List of talks

May 21, 2014, 2:15 p.m.
Tomasz Gogacz (Uniwersytet Wrocławski)
All instances termination of chase is undecidable
We show that all instances termination of chase is undecidable.More precisely, there is no algorithm deciding, for a given set Tconsisting of Tuple Generating Dependencies (a.k.a. Datalog+/- program), whether the T-chase on D will terminate …
May 14, 2014, 2:15 p.m.
Wojciech Czerwiński (Uniwersytet Warszawski)
joint work with Petr Jancar (Deciding branching bisimilarity on BPA in NEXPTIME)
Branching bisimilarity is a variant of the weak bisimilarity. Recently there was a big progress in deciding bisimilarity on context-free systems: decidability was shown. I will present the main ideas of this result and explain …
May 7, 2014, 2:15 p.m.
Paweł Parys (Uniwersytet Warszawski)
How Many Numbers Can a Lambda-term Contain?
It is well known, that simply-typed lambda-terms can be used to represent numbers, as well as some other data types, in particular tuples of numbers. We prove, however, that in a lambda-term of a fixed …
April 30, 2014, 2:15 p.m.
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No seminar this week
April 23, 2014, 2:15 p.m.
Mikołaj Bojańczyk (Uniwersytet Warszawski)
Star height via games
I will show a simplified proof of decidability for the star height problem. The simplified proof follows the same lines as the proof of Daniel Kirsten: first the star height problem is reduced to the …
April 16, 2014, 2:15 p.m.
Michał Skrzypczak (Uniwersytet Warszawski)
Kolmogorov's R-sets and regular tree languages
R-sets, introduced in 1928 by Andrey Kolmogorov, were designed as a wide class of well-behaved sets that can be described in a constructible way. One of the crucial properties of this class is universal measurability …
April 9, 2014, 2:15 p.m.
Michał Skrzypczak (Uniwersytet Warszawski)
Determinisation of History Deterministic Automata
A non-deterministic automaton is history deterministic if it is possible to resolve its choices in a way that depends only on the already read input. Such automata appear naturally in synthesis problems and qualitative models.One …
April 2, 2014, 2:15 p.m.
Szymon Toruńczyk (Uniwersytet Warszawski)
Turing Machine with Atoms and Descriptive Complexity
We relate Turing Machines with Atoms to a certain logic over finite structures. As an application to Descriptive Complexity Theory, within a substantial class of relational structures including Cai-Fürer-Immerman graphs, we precisely characterize those subclasses …
March 26, 2014, 2:15 p.m.
Luc Dartois (LIAFA, Paris)
Adding Modular predicates
When considering classes of regular languages, it is a primordial question to be able to determine if a given language belongs to it. Over fragments of logic, this question has been largely studied since McNaughton-Papert …
March 25, 2014, 2:15 p.m.
Olivier Serre (LIAFA, Paris)
Playing with Automata and Trees
Roughly speaking a finite automaton on infinite trees is a finite memory machine that takes as input an infinite node-labelled binary tree and processes it in a top-down fashion as follows. It starts at the …
March 19, 2014, 2:15 p.m.
Nathanaël Fijalkow (Uniwersytet Warszawski)
The value 1 problem for probabilistic automata
I will talk about probabilistic automata, which are automata assigning to each word a probability to be accepted. Specifically, I will be interested in the value 1 problem, which asks whether for a given probabilistic …
March 12, 2014, 2:15 p.m.
Joanna Ochremiak (Uniwersytet Warszawski)
joint work with Bartek Klin, Sławomir Lasota, Szymon Toruńczyk) - continuatio (Turing Machines with Atoms and Constraint Satisfaction Problems)
We study deterministic computability over sets with atoms. We characterize those alphabets for which Turing machines with atoms determinize. To this end, the determinization problem is expressed as a Constraint Satisfaction Problem, and a characterization …
March 5, 2014, 2:15 p.m.
Joanna Ochremiak (Uniwersytet Warszawski)
joint work with Bartek Klin, Sławomir Lasota, Szymon Toruńczyk (Turing Machines with Atoms and Constraint Satisfaction Problems)
We study deterministic computability over sets with atoms. We characterize those alphabets for which Turing machines with atoms determinize. To this end, the determinization problem is expressed as a Constraint Satisfaction Problem, and a characterization …
Feb. 26, 2014, 2:15 p.m.
Mikołaj Bojańczyk (Uniwersytet Warszawski)
Transducers with origin information
Call a string-to-string transducer regular if it can be realised by one of the following equivalent models: mso transductions, two-way deterministic automata with output, and streaming transducers with registers. In the talk, I will propose …
Feb. 19, 2014, 2:15 p.m.
Alessandro Facchini (Uniwersytet Warszawski)
joint work with F. Carreiro, Y. Venema and F. Zanasi (Weak MSO: Automata and Expressiveness Modulo Bisimilarity)
We prove that the bisimulation-invariant fragment of weak monadic second-order logic (WMSO) is equivalent to the fragment of the modal μ-calculus where the application of the least fixpoint operator μp.φ is restricted to formulas φ …