Computer algebra algorithms and routines for the computation of conservation laws and fixing of gauge in differential expressions

In this paper we present three different approaches for the determination o f conservation laws. For three corresponding REDUCE computer algebra progra ms CONLAW1/2/3 the necessary subroutines are described. All three programs use subroutines which remove redundant functions and constants in the gener al solution of the conservation law conditions. The corresponding algorithm is explained. Such a program is not only applicable in the context of comp uting conservation laws but whenever redundancy in differential expressions is to be removed or gauge freedom to be fixed. (C) 1999 Academic Press.