Caltech Home > PMA Home > Master Calendar > Logic Seminar
open search form
Wednesday, October 21, 2020
12:00 PM - 1:00 PM
Online Event

Logic Seminar

Borel and analytic sets in locales
Ronnie Chen, Department of Mathematics, University of Illinois at Urbana–Champaign,

A locale is, informally, a topological space without an underlying set of points, with only an abstract lattice of "open sets". Various results in the literature suggest that locale theory behaves in many ways like a generalization of descriptive set theory with countability restrictions removed. This talk will introduce locale theory from a descriptive set-theoretic point of view, and survey some known and new results which are common to both contexts. In particular, we will introduce the "∞∞-Borel hierarchy" of a locale, and sketch the existence of "σσ-analytic, non-∞∞-Borel sets".

For more information, please contact Math Department by phone at 626-395-4335 or by email at or visit