On pairs of definable orthogonal families

Abstract

We introduce the notion of an M-family of infinite subsets of \nn which is implicitly contained in the work of A. R. D. Mathias. We study the structure of a pair of orthogonal hereditary families \aaa and \bbb, where \aaa is analytic and \bbb is $C$-measurable and an M-family.Comment: 21 pages, no figures. Illinois Journal of Mathematics (to appear