Bazı kompleksler üzerine çalışmalar

Let R be any associative ring with unity and X be a class of R-modules. Thisthesis consists of three sections. In section 1, it is given some necessary definitionsand theorems in homological algebra which is used in other sections. In section 2,we define X-injective (projective) and DG(X-injective (projective)) complexes whichare generalizations of injective (projective) complexes and DG-injective (projective)complexes and obtain some properties. Moreover, we investigate C(X-injective (projective))preenvelopes (precovers). Finally, in section 3, we define an X*-complex anda class C(X*) and investigate C(X*)-envelope (cover) of a complex.