@techreport{R-88-01, TITLE = {Logic Programming with External Procedures: Introducing S-Unification}, AUTHOR = {Jacek Leszczylowski and Staffan Bonnier and Jan Maluszynski }, YEAR = {1988}, NUMBER = {R-88-01}, INSTITUTION = ida, ADDRESS = idaaddr, ABSTRACTURL = {/publications/cgi-bin/tr-fetch.pl?r-88-01+abstr}, ABSTRACT = {A motivation for this work is the problem of re-usability of existing traditional software in logic programs. It can be viewed in an abstract way as the problem of amalgamation of Horn clause logic with a term reduction system whose rewrite rules are not accessible and thus cannot be used for construction of E-unifiers. Therefore we introduce a new unification algorithm, called S-unification, which is a special incomplete case of E-unification. It has the property that whenever it succeeds the result is a singleton complete set of E-unifiers of the arguments. It may also fail or report that it is not able to solve the problem of E-unification for given arguments. If the algorithm fails the actual arguments have no E-unifier. The paper discusses the problem of amalgamation of external functional procedures in a logic program and gives a characterization of a class of amalgamated programs for which S-unification is complete.}, IDANR = {LiTH-IDA-R-88-01}