Strong Projective Witnesses

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Authors: Vera Fischer, Julia Millhouse
Cited by: 0

Abstract

We show Shelah's original creature forcing from 1984 strongly preserves tight mad families. In particular, answering questions of Fischer and Friedman and Friedman and Zdomskyy, we show the constellation $\aleph_1 = \mathfrak{a} < \mathfrak{s} = \aleph_2$ is consistent with the existence of a $Δ_3^1$ wellorder of the reals and tight mad families of sizes $\aleph_1, \aleph_2$ which are $Π_1^1, Π_2^1$-definable, respectively. Each of these projective definitions is of minimal possible complexity.

Fields of Study & Subjects

Advanced Topology and Set Theory Computability Logic AI Algorithms Advanced Banach Space Theory

Publication details

Journal / source
arXiv (Cornell University)
Publication date
13 January 2026
Document type
Preprint