CAN WE TRANSFORM LOGIC PROGRAMS INTO ATTRIBUTE GRAMMARS?

Abstract

In this paper we study the relationship between Attribute Grammars and Logic Programs, concentrating on transforming logic programs into attribute grammars. This has potential applications in compilation techniques for logic programs. It does not seem possible to transform arbitrary Logic Programs into Attribute Grammars, basically because the same logic variables can sometimes be used as input and sometimes as output. We introduce the notion of an Abstract Attribute Grammar, which is similar to that of an Attribute Grammar with the exception that attributes are not classified into inherited and synthesized, and that the semantic equations are replaced by restriction sets. These sets represent a restriction on the values of attribute occurrences namely, all elements within each set have to be equal. We give an effective translation schema which produces an equivalent Abstract Attribute Grammar for a given Logic Program. We provide a formal proof of this equivalence. We then proceed to classify a class of Abstract Attribute Grammars that can be transformed into Attribute Grammars, and show how to achieve this transformation. By composing both transformations one can transform certain logic programs into attribute grammars. Complete proofs ar5e given.