Given words w_1 and w_2 over the generators of an fp-algebra A, create the relation w_1 = w_2. Note that this relation is not automatically added to the existing set of defining relations R for A. It may be added to R, for example, through use of the quo-constructor (see below).

Given a relation r over the generators of A, return the left hand side of the relation r. The object returned is a word over the generators of A.

Given a relation r over the generators of A, return the right hand side of the relation r. The object returned is a word over the generators of A.