This file can be used to add scheduled events to your calendar, however every program is unique. Below you will find what information is available, but if nothing else works try creating a new calendar in your program and using
http://math.colorado.edu/seminars/ics/allo.ics
as the source.
Thunderbird
The Algebra and Logic seminar is a research and learning seminar organized by the algebra and logic research group of the Department of Mathematics at the University of Colorado at Boulder. The scope of the seminar includes all topics with links to algebra, logic, or their applications, like general algebra, logic, model theory, category theory, set theory, set-theoretic topology, or theoretical computer science. If you have questions regarding this seminar, please contact Keith Kearnes or Peter Mayr.
The Bodirsky-Pinsker conjecture is an infinite counterpart to the Feder-Vardi dichotomy conjecture for Constraint Satisfaction Problems (CSPs) with finite templates. While the latter has been confirmed independently by Bulatov and Zhuk, the former remains wide open. In this talk, we shed light on three meta-problems regarding the scope of this conjecture.
Our first result provides a significant structural simplification of this scope: we prove that the conjecture is equivalent to its restriction to templates without algebraicity, a crucial assumption in many powerful classification methods. The second result provides a simplification of algebraic nature: any algebraic condition characterizing any complexity class within the conjecture must be satisfiable by injections. In particular, this offers insight into which universal-algebraic conditions for the complexity of finite-template CSPs may be successfully lifted to the infinite case. The third result we are going to explore links the conjecture to so-called Promise Constraint Satisfaction Problems (PCSPs): using the construction from the first result, virtually every structure from the scope of the conjecture allows us to construct a sandwich structure for a non-finitely tractable finite-domain PCSP.
This is joint work with Michael Pinsker, Jakub Rydval and Christoph Spiess.
Eliminating algebraicity and enforcing injectivity in infinite-domain constraint satisfaction
I shall introduce and describe the subject of modal model theory, in which one studies a mathematical structure within a class of similar structures under an extension concept, giving rise to mathematically natural notions of possibility and necessity, a form of mathematical potentialism. We study the class of all graphs, or all groups, all fields, all orders, or what have you; a natural case is the class of all models of a fixed first-order theory. In this talk, I shall describe some of the resulting elementary theory, particularly the remarkable expressive power of modal graph theory. This is joint work with my Oxford student Wojciech Woloszyn.
The Constraint Satisfaction Problem (CSP) over a structure with a finite relational signature is the problem of deciding whether a given finite input structure with the same signature as has a homomorphism to . According to the famous result of Bulatov and Zhuk we know that CSPs over finite template structures exhibit a complexity dichotomy: they are all in or -complete. Generalizing this theorem to infinite structures has been a topic of active research in the past few decades. A currently standing conjecture in this direction is by Bodirsky and Pinsker which states that the same complexity dichotomy holds for first-order reducts of finitely bounded homogeneous structures. In my talk I am exploring some ideas on how this conjecture could be attacked under some strong model theoretical assumptions such as -stability or first-order interpretability in the pure set. This approach often requires a detailed understanding of structures arising in this context which also leads to some questions in model theory that could be of independent interest.
This is joint work with Manuel Bodirsky and Paolo Marimon.
Eliminating algebraicity and enforcing injectivity in infinite-domain constraint satisfaction