Semantic-driven Generation with LFG- and PATR-style Grammars

To find an appropriate utterance for a semantic representation is a problem normally treated in the domain of (tactical) natural language generation. For unification-based approaches, like LFG, PATR, or HPSG (Kaplan and Bresnan 1982; Shieber et al. 1983; Pollard and Sag 1994), this problem turns out to be a formal problem of the underlying grammar formalism, when the mapping between strings and semantic representations is defined by the grammar. Semantic representations are then encoded in a separate part of the feature structures (henceforth f-structures) that are assigned to the sentences by the grammar. This is normally achieved by a distinct attribute SF.M (or an additional a-projection that is formally reconstructable by such an attribute) whose value is intended to represent the semantics of the sentence the f-structure is assigned to. The f-structure given in (1), which might be assigned to the sentence John arrives by a unification grammar for English, is a simple example.