Isogroups of differential equations using algebraic computing

We describe the Liesymm package, implemented in the symbolic computing system MAPLE, for obtaining the determining equations of the isogroup of a system of partial differential equations. Liesymm fully automates the Harrison-Estabrook procedure which uses Cartan's formulation in terms of differential forms. It also includes a number of routines which assist the user in integrating the determining equations. Liesymm has been implemented in such a way as to provide the user with a number of useful interactive tools for working with differential forms. In addition, it can also generate a "suitable" initial set of differential forms directly from the given partial differential equations and as such can be used at a level that obviates any need for familiarity with forms.