Foundations of Relative Homological Algebra

Download or read book Foundations of Relative Homological Algebra written by Samuel Eilenberg and published by American Mathematical Soc.. This book was released on 1965 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main notion of this paper is that of a "projective class of sequences" in an arbitrary (pointed) category. Each such class carries with it its own projective objects. One can then talk about projective resolutions, and if the category is additive, all the usual properties of the resolutions hold. In particular, this will permit the development of homological algebra in some additive categories which are not abelian, e.g., the category of comodules over a coalgebra over an arbitrary commutative ring.