Absolute integral closures of commutative rings

Abstract

Absolute integral closures of general commutative unital rings are explored. All rings admit absolute integral closures, but in general they are not unique. In fact, among the reduced rings with finitely many minimal prime ideals, finite products of domains are the only rings for which they are unique. And arguments using model theory suggest that the same holds for all infinite rings that are finite products of connected rings. Universal absolute integral closures, which contain every absolute integral closure of a given ring, are shown to exist for certain subrings of products of domains