The Cotangent Complex of a Morphism

Abstract

Let A -> B -y C be a sequence of ring homomorphisms. (Unless otherwise noted all rings will be commutative with unit, and all modules and homomorphisms will be unitary.) Let QBM, QCM, Q.c/B denote the respective modules of Kahler differentials ( 1.1). Then one obtains easily the following exact sequence of C-modules: