Definable maximal discrete sets in forcing extensions

David Schrittesser, Asger Törnquist

Let $\mathcal{R}$ be a ${\Sigma }_1^1$ binary relation, and recall that a set $A$ is $\mathcal{R}$-discrete if no two elements of $A$ are related by $\mathcal{R}$. We show that in the Sacks a…