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A SEPARATION RESULT FOR COUNTABLE UNIONS OF BOREL RECTANGLES

Published online by Cambridge University Press:  22 February 2019

DOMINIQUE LECOMTE*
Affiliation:
UNIVERSITÉ PARIS 6, INSTITUT DE MATHÉMATIQUES DE JUSSIEU-PARIS RIVE GAUCHE PROJET ANALYSE FONCTIONNELLE, COULOIR 16-26 4ÈME ÉTAGE, CASE 247, 4, PLACE JUSSIEU 75 252 PARIS CEDEX 05, FRANCE AND UNIVERSITÉ DE PICARDIE, I.U.T. DE L’OISE, SITE DE CREIL 13, ALLÉE DE LA FAÏENCERIE 60 107 CREIL, FRANCE E-mail: [email protected]

Abstract

We provide dichotomy results characterizing when two disjoint analytic binary relations can be separated by a countable union of ${\bf{\Sigma }}_1^0 \times {\bf{\Sigma }}_\xi ^0$ sets, or by a ${\bf{\Pi }}_1^0 \times {\bf{\Pi }}_\xi ^0$ set.

Type
Articles
Copyright
Copyright © The Association for Symbolic Logic 2019 

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References

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