André-Quillen cohomology theory of an algebra over an operad

Following the ideas of Quillen and by means of model category structures, Hinich, Goerss and Hopkins have developped a cohomology theory for (simplicial) algebras over a (simplicial) operad. Thank to Koszul duality theory of operads, we describe the cotangent complex to make these theories explicit in the differential graded setting. We recover the known theories as Hochschild cohomology theory for associative algebras and Chevalley-Eilenberg cohomology theory for Lie algebras and we define the new case of homotopy algebras. We study the general properties of such cohomology theories and we give an effective criterium to determine whether a cohomology theory is an Ext-functor. We show that it is always the case for homotopy algebras.