设X 为一个左R-模类. 本文引入了CE X-内射复形和CE X-平坦复形的概念, 在X
满足一定条件的情况下, 讨论了这两类复形的联系, 给出了这两类复形的一些等价刻画. Abstract …

Recall that a ring R is said to be left coherent [2] if every finitely generated left ideal of R is
finitely presented. Coherent rings and their generalizations have been studied extensively …

For a Quillen exact category CC endowed with two exact structures DD and EE such that E
⊆ DE⊆ D, an object X of CC is called E E-divisible (respectively E E-flat) if every short exact …

Let R be a ring and n be a positive integer. R is called left n-coherent, if every n-presented
left R-module is (n+ 1)(n+ 1)-presented. A left R-module M is called (n, 0)-injective if Ext …

Recall that a ring R is said to be left coherent [2, 7] if every finitely generated left ideal of R is
finitely presented, a ring R is said to be left semihereditary if every finitely generated left …

Let $ R $ be a ring and $\mathscr {C} $ be a class of some finitely presented left $ R $-
modules. A left $ R $-module $ M $ is called $\mathscr {C} $-injective if Ext $^ 1_R (C, M) …