Separating weak and full universality for F-sigma relations
Construct an $F_\sigma$ relation with the weak universality property but not the universality property, and determine whether such a relation can induce a $\sigma$-ideal that is provably $\mathbf{\Delta}^1_2$ on $\mathbf\Sigma^1_1$.
References
We do not know whether the two universality notions can be separated with an $F_\sigma$ relation.
Is there an $F_\sigma$ relation with the weak universality property but not the universality property? What if the induced ideal is also provably $\mathbf{\Delta}1_2$ on $\mathbf\Sigma1_1$?
— Universal domination and idealized forcing
(2608.18964 - Schilhan, 19 Aug 2026) in Question labelled \ref{quest:Fsigmasepuniv}, Section 3, subsection “Simple examples”