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Cotygodniowe seminarium badawcze
2020-03-11, godz. 14:15, 5050
2020-03-04, godz. 14:15, 5050
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 relevant for program verification o...
2020-02-26, godz. 14:15, 5050
Mikołaj Bojańczyk (Uniwersytet Warszawski)
First-order tree-to-tree functions (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, ...
2020-02-05, godz. 14:15, 5050
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 two pebbles if and only if its output has quadratic size in its input, a transducer with thre...
2020-01-29, godz. 14:15, 5050
Piotr Hofman (Uniwersytet Warszawski)
Generalized linear equations with unordered data (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 extension of Petri Nets allows more precise modeling than normal Petri Nets. Of course, comp...
2020-01-22, godz. 14:15, 5050
Pierre Simon (UC Berkeley)
Model theory of order-like and tree-like homogeneous structure
I will discuss results towards a model-theoretic classification of order-like homogeneous structures, including for instance all structures FO-definable in a dense linear order. I will also mention ongoing work towards extending this classification to include structures FO-definable in dense tre...
2020-01-15, godz. 14:15, 5050
Wojciech Czerwiński (Uniwersytet Warszawski)
I will present a few recent results about reachability problem for fixed dimensional VASSes. There results invalidate some previously posed conjectures and show that the problem is harder than previously expected to be. ...
2020-01-08, godz. 14:15, 5050
Paweł Parys (Uniwersytet Warszawski)
Bisimulation Finiteness of Pushdown Systems Is Elementary (joint work with Stefan Göller)
We show that in case a pushdown system is bisimulation equivalent to a finite system, then there is already a bisimulation equivalent finite system whose size is elementarily bounded in the description size of the pushdown system. As a consequence we obtain that it is elementarily decidable if a g...
2019-12-18, godz. 14:15, 5050
Michał Wrocławski (Uniwersytet Warszawski)
How computability depends on notation?
We study abstract notations for natural numbers, which may differ from standard notations, so that the functions and relations classically uncomputable become computable, and vice versa. This question was raised by a philosopher Stewart Shapiro in course of the debate on Church-Turin...
2019-12-11, godz. 14:15, 5050
Sławomir Lasota (Uniwersytet Warszawski)
The aim is to present a technical core of a recently obtained TOWER lower bound for the reachability problem of Petri nets, model equivalent to vector addition systems with states or to nondeterministic counter machines without zero tests. Using an equivalent syntax of 'counter programs...
