Implementational Issues in GCLA: Compiling Control

The paper describes the basic implementation of GCLA II's control level. The basis of the implementation is a compiling scheme for transforming inference rules and strategies operating on the object level to an interpreter in Prolog, where the inference rules of the control level are coded inline. This is possible since the operational semantics of the control level is deterministic, i.e. the choice of inference rule to apply on a control level goal is determined solely by the parts of the goal. To handle dynamic clauses, a context list, accessible through some new C-functions linked together with the Prolog system. GCLA I and GCLA II are described shortly, followed by a discussion of a Horn clause representation of inference rules versus functions coding inference rules. Then the transformation of inference rules and strategies is described followed by some examples