In algebraic geometry over a variety of universal algebras Θ, the group Aut(Θ 0 ) of automorphisms of the category Θ 0 of finitely generated free algebras of Θ is of great importance. In this paper, semi-inner automorphisms are defined for the categories of free (semi)modules and free Lie modules; then, under natural conditions on a (semi)ring, it is shown that all automorphisms of those categories are semi-inner. We thus prove that for a variety R M of semimodules over an IBN-semiring R (an IBN-semiring is a semiring analog of a ring with IBN), all automorphisms of Aut( R M 0 ) are semi-inner. Therefore, for a wide range of rings, this solves Problem 12 left open in [22]; in particular, for Artinian (Noetherian, P I-) rings R, or a division semiring R, all automorphisms of Aut( R M 0 ) are semi-inner. April 30, 2005April 30, . 1991 Mathematics Subject Classification. Primary 16Y60, 16D90,16D99, 17B01; Secondary 08A35, 08C05.
Date:Key words and phrases. free module, free semimodule over semiring, free modules over Lie algebras, semi-inner automorphism.