Characterizing $S$-projective modules and $S$-semisimple rings by uniformity

TL;DR

This paper introduces and characterizes $u$-$S$-projective and $u$-$S$-semisimple modules over rings with a multiplicative subset, exploring their properties and the structure of rings where all free modules are $u$-$S$-semisimple.

Contribution

It defines the concepts of $u$-$S$-projective and $u$-$S$-semisimple modules and provides characterizations of rings where free modules are $u$-$S$-semisimple, extending module theory.

Findings

Characterizations of $u$-$S$-projective modules.

Introduction of $u$-$S$-semisimple modules.

Characterizations of $u$-$S$-semisimple rings.

Abstract

Let $R$ be a ring and $S$ a multiplicative subset of $R$. An $R$-module $P$ is called uniformly $S$-projective provided that the induced sequence $0\rightarrow \mathrm{Hom}_R(P,A)\rightarrow \mathrm{Hom}_R(P,B)\rightarrow \mathrm{Hom}_R(P,C)\rightarrow 0$ is $u$-$S$-exact for any $u$-$S$-short exact sequence $0\rightarrow A\rightarrow B\rightarrow C\rightarrow 0$. Some characterizations and properties of $u$-$S$-projective modules are obtained. The notion of $u$-$S$-semisimple modules is also introduced. A ring $R$ is called a $u$-$S$-semisimple ring provided that any free $R$-module is $u$-$S$-semisimple. Several characterizations of $u$-$S$-semisimple rings are provided in terms of $u$-$S$-semisimple modules, $u$-$S$-projective modules, $u$-$S$-injective modules and $u$-$S$-split $u$-$S$-exact sequences.