Implementational Issues in GCLA: A-Sufficiency and Definiens Operation

We present algorithms for computing A-sufficient substitutions and constraint sets together with the def'miens operation. These operations are primitive operations in the language GCLA. The paper first defines those primitives, which together form a dual rule to SLD resolution, and then describes the different algorithms and some of their properties together with examples. One of the algorithms shows how a deffmition can be compiled into a representation holding all possible A-sufficient substitutions/constralnt sets together with their corresponding deffmiens. This representation makes the computation in nmtime of a def'miens and an A-sufficient substitution/constraint set having the same complexity as the operation c l a u s e / 2 in Prolog. The paper also describes the generalisation from unification (sets of equalities) to constraint sets and satisfiability of systems of equalities and inequalities.