Extraposition grammars
Fernando M. B. Pereira · 1981
This paper presents a grammar formalism for natural language analysis, called extraposition grammars (XGs), based on the subset of predicate calculus known as definite, or Horn, clauses. It is argued that certain important linguistic phenomena, collectively known in transformational grammar as left extra- position, can be described better in XGs than in earlier grammar formalisms based on definite clauses