Natural language parsing was one of the main motivations from which Prolog was developed Metamorphosis grammars, designed by Alain Colmerauer at GIA Marseille, was the first logic-based formalism for natural language par'Sing" These grammars have inspired a number of other logic-based grammar formalisms and implementations which ar'e now commonly used and some of which are still under intense research. These formalisms are very close per se to Metamorphosis grammar'S, sOl)1e of them were motivated by the need to enhance the ease of writing grammar' rules, other'S support deeper linguistic motivations and concepts.