ABSTRACT
This chapter illustrates the theoretical framework, and gives an overview of the fundamental principles and the technical apparatus of Head-driven Phrase Structure Grammar (HPSG) as laid out in Pollard and Sag 1987, 1994. One of the fundamental properties of HPSG is that it is a unification-based linguistic theory and, in this respect, it has much in common with Categorial Grammar, Generalized Phrase Structure Grammar, and Lexical-Functional Grammar. A linguistic expression, referred to as a sign in HPSG, is modelled in a system of sorted feature structures. The chapter also illustrates the SYNSEM features to show how the mechanism of structure sharing works in various aspects of syntax and semantics. The lexical specification for the SUBCAT feature is carried by verbs and other lexical items that head phrases. HPSG has a set of phrase structure “rules” called Immediate Dominance schemata. The postulation of lexical rules has been defended in lexicalist approaches for its advantage of simplifying the organization of the lexicon.
