Descent of properties of rings and pairs of rings to fixed rings

Abstract

Let G be a group acting via ring automorphisms on an integral domain R. A ring-theoretic property of R is said to be G-invariant, if $R^G$ also has the property, where $R^G=\{r\in R \ | \ \sigma (r)=r \ \text {for all} \ \sigma \in G\},$ the fixed ring of the action. In this paper we prove the following classes of rings are invariant under the operation $R\rightarrow R^G:$ locally pqr domains, Strong G-domains, G-domains, Hilbert rings, S-strong rings and root-closed domains. Further let $\mathscr {P}$ be a ring theoretic property and $R\subseteq S$ be a ring extension. A pair of rings (R, S) is said to be a $\mathscr {P}$-pair, if T satisfies $\mathscr {P}$ for each intermediate ring $R\subseteq T\subseteq S.$ We also prove that the property $\mathscr {P}$ descends from $(R,S)\rightarrow (R^G, S^G)$ in several cases. For instance, if $\mathscr {P}=$ Going-down, Pseudo-valuation domain and “finite length of intermediate chains of domains”, we show each of these properties successfully transfer from $(R,S)\rightarrow (R^G, S^G).$