The Laczkovich-Komjath Property for Coanalytic
Equivalence Relations
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Su Gao, Steve Jackson, and Vincent Kieftenbeld
Abstract
Let E be a coanalytic equivalence relation
on a Polish space X and (An) a sequence of analytic subsets of X. We prove that if limsupK An meets
uncountably many E-equivalence
classes for every K in [ω]ω, then there
exists a K in [ω]ω such that ∩K An
contains a perfect set of pairwise E-inequivalent
elements.
Table of Contents
1. Introduction
2. Coding and sets
3. Canonical cofinal sequences
4. A completely good pair
5. Proof of the main theorem
References