Self-injective algebras and the second Hochschild cohomology group

In this thesis we study the second Hochschild cohomology group HH 2(Lambda) of a finite dimensional algebra Lambda. In particular, we determine HH2(Lambda) where Lambda is a finite dimensional self-injective algebra of finite representation type over an algebraically closed field K and show that this group is zero for most such Lambda; we give a basis for HH2(Lambda) in the few cases where it is not zero.;Then we consider algebras of tame representation type; more specifically, we study finite dimensional self-injective one parametric tame algebras which are not weakly symmetric. Here we show that HH2(Lambda) is non-zero and find a non-zero element eta in HH2(Lambda) and an associative deformation Lambdaeta of Lambda.