四元拟循环码的代数结构

本文研究了Z4上的拟循环码,证明了Z4上的长度为mn的拟循环码等价于一个An的A-子模,其中A=Z4[x]/(xm-1),在m为奇数的时候,所有的拟循环码均可以分解为一些有限数目的循环不可约A-子模的直和。     

广义逆多项式模的子模和投射覆盖

从子模、本质子模、多余子模等方面探讨广义逆多项式模M[S]与其系数模M之间的关系，定义左R-模同态λ：M→N的诱导左[[R^s,≤]]—模同态λ^*：M[S]→N[S]，得到结论：若(M[S]，λ^*)是N[S]的投射覆盖，则(M，A)是N的投射覆盖。     

On closed weak supplemented modules

INTRODUCTION In recent years theory of extending modules and rings has come to play an important role in the theory of rings and modules. A module is called an extending module (or CS-module) if every submodule is essen- tial in a direct summand, or equivalently, every closed submodule is a direct summand. Although this gen- eralization of injectivity is extremely useful, it does not satisfy some important properties. For example, direct sums of extending modules need not be ex- tending;…