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BEGIN:VEVENT
UID:2021042203044120210406T11000020210406T1150006080e7c95aeeb@uic.edu
CATEGORIES:MEETING
STATUS:TENTATIVE
DTSTAMP:20210421T091802
DTSTART:20210406T110000
DTEND:20210406T115000
SUMMARY:Logic Seminar: Some finite basis results for quasi-orders, by Raphael Carroy
DESCRIPTION:Raphael Carroy (University of Turin): Some finite basis results for quasi-orders What is a finite basis result for a quasi-order? A quasi-order is a transitive and reflexive relation on a set (or a class). Given a quasi-order $\leq_Q$ on a set $Q$ and a subset $A$ of $Q$, a basis for $A$ is a subset $B$ of $A$ such that for all $a \in A$ there exists $b \in B$ so that $b \leq_Q a$. The quasi-order $\leq_Q$ has a symmetrization: $p \equiv_Q q$ if and only if $p \leq_Q q$ and $q \leq_Q p$, which is an equivalence relation. We say that the basis $B$ is finite if its quotient by $\equiv_Q$ is finite. We consider the existence of a morphism between two structures in a given class as a quasi-order on the class of structures. I will talk about some finite basis results on classes of graphs and classes of functions for various notions of morphisms, and the interplay between them. Please click here to make changes to, or delete, this seminar announcement.
LOCATION:Zoom Chicago IL
CLASS:PRIVATE
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