ABSTRACT
Grammatical formalism used in computational linguistics that is derived from definite clause grammar and metamorphosis grammar and that introduces a particular type of rule for treating ‘left extraposition’ (e.g. the unbounded movement found in interrogative sentences and in relative clauses in English and French, trace theory). In extraposition grammar, the description of structure (i.e. a non-terminal (‘motivated’) category, followed by an arbitrary chain, followed by an empty non-terminal category (‘trace’) is placed on the left side of a rule that expands into a chain without a ‘trace.’ Thus, given the rule we may begin with: ‘rel. marker…trace rel. pronoun.’ The mouse rel. marker the cat chased trace squeaks to derive The mouse rel. pronoun the cat chased squeaks (‘rel. marker’ and ‘trace’ are non-terminal categories,’…‘stands for an arbitrary chain). In this way, on the one hand the structural relation between ‘motivated’ categories and ‘traces’ is made clear in a rule, on the other hand it is no longer necessary to expand a non-terminal category into an empty chain.
