n-余挠模和n-平坦模（英文）

n-cotorsion Modules and n-fiat Modules

本文引入n-余挠模并给出一些性质,证明了右n-凝聚环上一类n-凝聚左R-模是包络的,证明了一类n-平坦左R-模是覆盖的和预包络的,研究了由n-平坦预覆盖和预包络诱导的n-平坦维数.

In this paper, we introduce n-cotorsion modules and study some properties of them. Over right n-coherent rings, we prove that the class of n-cotorsion left R-modules is enveloping. Furthermore, we prove the class of n-flat left R-modules is covering and preenveloping and investigate the n-flat dimensions induced by n-flat precovers and preenvelopes.