RIF Core must cover pure Prolog
It must be straight-forward to convert the syntactic structures of any Pure Prolog ruleset into RIF Core and to convert them back again, ending up with the same thing.
Position in DC structure
Level: Requirement [PROPOSED]
Pure Prolog is a widely-studied and widely-implemented rule language. It is a language of definite (positive) Horn clauses, and so falls within the Phase 1 scope (RIF Core). It will allow people to experiment with using RIF among a wide variety of common rule systems.