Pi-Extendıng Modüllerin Dik Toplananları Üzerine

Abstract

This work consists of five chapters. In the first chapter, the basic properties of useful certain kind of submodules in module and ring theory which are named as essential and complement submodules are given. In the second chapter, $CS$ (extending), continuous and quasi-continuous modules which are based on aforementioned special submodules and originated John von Neumann's work are provided. The third chapter contains two generalizations of $CS$-modules, called $C_{11}$ and $C_{12}$ in the literature, such that preserve some kind of module properties that are missing for $CS$-modules. In chapter four, we introduce projection invariant extending modules via restricting the CS condition on submodules which are invariant under certain kind of endomorphisms, we investigate fundamental properties and relationships of this class of modules with the other classes of modules.