True propositions of sets are those that hold in the up to unique isomorphism model of the theory Ordinals defined here: https://papers.ssrn.com/sol3/papers.cf

True propositions of sets are those that hold in the up to unique isomorphism model of the theory Ordinals defined here: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3457802 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3457802