Article ID Journal Published Year Pages File Type
6424785 Annals of Pure and Applied Logic 2013 9 Pages PDF
Abstract

In this article we introduce and study the notion of operational closure: a transitive set d is called operationally closed iff it contains all constants of OST and any operation f∈d applied to an element a∈d yields an element fa∈d, provided that f applied to a has a value at all. We will show that there is a direct relationship between operational closure and stability in the sense that operationally closed sets behave like Σ1 substructures of the universe. This leads to our final result that OST plus the axiom (OLim), claiming that any set is element of an operationally closed set, is proof-theoretically equivalent to the system KP+(Σ1-Sep) of Kripke-Platek set theory with infinity and Σ1 separation. We also characterize the system OST plus the existence of one operationally closed set in terms of Kripke-Platek set theory with infinity and a parameter-free version of Σ1 separation.

Related Topics
Physical Sciences and Engineering Mathematics Logic
Authors
,