A separation result for countable unions of Borel rectangles (1708.00642v1)

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