Essential countability of treeable equivalence relations

Autor: Lecomte, Dominique, Clemens, John D., Miller, Benjamin D.
Přispěvatelé: Institut de Mathématiques de Jussieu (IMJ), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut für mathematische Logik und Grundlagenforschung, Fachbereich Mathematik und Informatik, Westfälische Wilhelms-Universität Münster (WWU), Westfälische Wilhelms-Universität Münster = University of Münster (WWU)
Jazyk: angličtina
Rok vydání: 2014
Předmět:
Popis: We establish a dichotomy theorem characterizing the circumstances under which a treeable Borel equivalence relation E is essentially countable. Under additional topological assumptions on the treeing, we in fact show that E is essentially countable if and only if there is no continuous embedding of E1 into E. Our techniques also yield the first classical proof of the analogous result for hypersmooth equivalence relations, and allow us to show that up to continuous Kakutani embeddability, there is a minimum Borel function which is not essentially countable-to-one.
Databáze: OpenAIRE