Weekly research seminar
Organizers
 prof. dr hab. Mikołaj Bojańczyk
 prof. dr hab. Damian Niwiński
Information
Wednesdays, 2:15 p.m. , room: 5050Research fields
List of talks

Oct. 5, 2022, 2:15 p.m.
Nguyễn Lê Thành Dũng (École normale supérieure de Lyon)
A transducer model for simply typed λdefinable functions
Among the natural ways to define functions ℕ^k > ℕ in the simply typed λcalculus, one of them allows hyperexponential growth (any tower of exponentials) but excludes many basic functions such as subtraction and equality, …

June 15, 2022, 2:15 p.m.
Albert Gutowski (MIM UW)
Finite entailment of UCRPQs over ALC ontologies
We solve finite ontologymediated query entailment for ontologies expressed in ALC (a description logic, closely related to (multi)modal logic) and queries expressed as UCRPQs (extending UCQs  unions of conjunctive queries  with constraints on …

June 8, 2022, 2:15 p.m.
Jędrzej Kołodziejski (MIM UW)
Multivalued Fixpoint Logic
We investigate multivalued fixpoint logic, an extension of the classical mucalculus where logical values range over a fixed complete lattice A equipped with monotone operations as connectives. We present equivalent game semantics for the logic …

June 1, 2022, 2:15 p.m.
Michał Skrzypczak (MIM UW)
Computing measures of regular languages via fixpoint expressions
During the talk I will present our ongoing work with Damian Niwiński and Paweł Parys on computing measures of regular languages. Our approach (following earlier results with Marcin Przybyłko) is to reduce the problem to …

May 25, 2022, 2:15 p.m.
Olivier Carton; Sebastian Maneth (University of Paris; University of Bremen)
Tight links between normality and automata; Two Applications of the Parikh Property
Abstract (Tight links between normality and automata): Normality has been introduced by É. Borel more than one hundred years ago. A real number is normal to an integer base if, in its infinite expansion expressed …

May 11, 2022, 2:15 p.m.
Filip Mazowiecki (MIM UW)
The complexity of soundness in workflow nets
Workflow nets are a popular variant of Petri nets that allow for algorithmic formal analysis of business processes. The central decision problems concerning workflow nets deal with soundness, where the initial and final configurations are …

April 27, 2022, 2:15 p.m.
David Purser (MIM UW)
The Skolem Problem for Simple Linear Recurrence Sequences
The Skolem Problem, asks to decide whether a linear recurrence sequence has a zero term. The SkolemMahlerLech theorem states that the set of zeros of a linear recurrence sequence is the union of a finite …

April 20, 2022, 2:15 p.m.
Wojciech Przybyszewski (MIM UW)
Definability of neighborhoods in graphs of bounded twinwidth and its consequences
During the talk, we will study set systems formed by neighborhoods in graphs of bounded twinwidth. In particular, we will show how, for a given graph from a class of graphs of bounded twinwidth, to …

April 6, 2022, 2:15 p.m.
Rose McCarty (MIM UW)
Vertexminors: dense graphs from sparse graphs
Structural graph theory has traditionally focused on graph classes that are sparse (that is, only contain graphs with few edges). Lately, however, there has been an ongoing shift towards the dense setting. In the first …

March 23, 2022, 2:15 p.m.
Marcin Jurdziński (University of Warwick)
Attractor decompositions and their applications in games and automata
An attractor decomposition is a natural inductively defined decomposition of a graph that satisfies the parity condition, and its “shape” can be described by an ordered tree. The McNaughtonZielonka algorithm implicitly produces an attractor decomposition …

March 16, 2022, 2:15 p.m.
Michał Pilipczuk (MIM UW)
Dimension of posets of bounded cliquewidth
Dimension and boolean dimension are two structural measures for posets (partially ordered sets). Roughly speaking, they measure the minimum number of linear orders sufficient for encoding the poset. We will discuss a proof that posets …

March 9, 2022, 2:15 p.m.
Marie Fortin (University of Liverpool)
How undecidable are HyperLTL and HyperCTL*?
Temporal logics for the specification of informationflow properties are able to express relations between multiple executions of a system. Two of the most important such logics are HyperLTL and HyperCTL*, which generalise LTL and CTL* …

March 2, 2022, 2:15 p.m.
Rafał Stefański (MIM UW)
Singleuse 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 …

Jan. 26, 2022, 2:15 p.m.
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 …

Jan. 19, 2022, 2:15 p.m.
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 Ackermanncomplete a lot …