On Tuesday, November 19, we continue our seminar in Logic, Set Theory and Topology.
Please note new time and place.
Time is 10:30–12:00.
Place: Class No. 129, bldg 90
Speaker: Dmitry Sustretov (BGU)
Title: Generalized imaginaries and Galois cohomology
Given a theory T one is interested in classification (up to bi-interpretability)
of its expansions T’ with sorts internal to sorts
of T. Such expansions can be described in terms of certain definable
or type-definable groupoids, called liaison groupoids, introduced by
Hrushovski. Bi-interpetability classes of internal sorts correspond to
classes of liaison groupoids modulo certain equivalence. In this talk
I will explain how equivalence classes of connected groupoids
definable over A that trivialize over acl(A) can be described in terms
of cohomology of the Galois group Gal(acl(A)/dcl(A)). I will then
apply this correspondence to give criteria for interpretability of
“non-standard” Zariski geometries of Zilber in an algebraically closed field.