Logic Program Schemas, Semi-Uni cation and Constraints

The use of schemas is a classical way of synthesizing, transforming and analyzing logic programs. Operations on schemas are needed, in particular, the semi-uniication of schemas with programs. Since the schemas used in the paper are second-order objects, the related semi-uniication is the second-order semi-uniication, which is decidable but NP-complete. The non-determinism implied by the NP-completeness slows down the search for a substitution. The present paper expresses the semi-uniication process over schemas as rewriting and reduction rules. Global and local constraints are associated to the schema to extend the expressivity of schema description and to speed up the search for a second-order substitution between programs and schemas. CLP techniques and notations are used.