A library for computing with elements of the differential algebra over a (quotient) ring.
To compute in this algebra, a non-commutative ring with additional variables
dx_1,...,dx_n and 'exterior' relations between this variables is used. In the case of a
quotient ring, the defining ideal and its image under the universal derivation are added as relations.
The differential forms themselves are defined via an additional type 'difform'. Objects
of this type carry as an attribute a polynomial in the differential algebra and make it
available over the basering.
Additionally, the universal derivation is available as a procedure and the differentials between the
graded parts of the differential algebra can be applied to differential forms.
The library also supports derivations: maps from the first graded part of the differential algebra
to the basering. These are defined via the type 'derivation' and there are procedures for basic arithmetic
operations, evaluation and Lie-derivative.