Relationships between Principles of Choice in Second-Order Henkin Structures

Abstract

We deal with the strength of classical second-order versions of the Axiom of Choice (AC) in second-order predicate logic (PLII) with Henkin interpretation (HPL). We use the known relationships between the so-called Zermelo-Asser axioms and the so-called Russell-Asser axioms and prove relationships between the so-called Ackermann axioms and the Zermelo-Asser axioms and between the so-called Asser axioms and the Zermelo-Asser axioms. In particular, we give the technical details of the proofs of our results presented at the DMV Annual Meeting 2022.