$\Sigma^1_2$ and $\Pi^1_1$ mad families

Abstract

We answer in the affirmative the following question of Jörg Brendle: If there is a $\Sigma^1_2$ mad family, is there then a $\Pi^1_1$ mad family?

Asger Törnquist. "$\Sigma^1_2$ and $\Pi^1_1$ mad families." J. Symbolic Logic 78 (4) 1181 - 1182, December 2013. https://doi.org/10.2178/jsl.7804080

Published: December 2013

First available in Project Euclid: 5 January 2014

MathSciNet: MR3156517

Digital Object Identifier: 10.2178/jsl.7804080