Fakultaet fuer Mathematik, Universitaet Wien
Nordbergstrasse 15, 1090 Wien, Austria
Abstract. Degenerations, contractions and deformations of various algebraic structures play an important role in mathematics and physics. There are many different definitions and special cases of these notions. We try to give a general definition which unifies these notions and shows the connections among them. Here we focus on contractions of Lie algebras and algebraic groups.
AMSclassification. 14Lxx, 17Bxx, 81R05.
Keywords. Contractions, Lie algebras, affine algebraic groups, affine group schemes.