The Alpino grammar is an extension of the successful OVIS grammar [23,24], a lexicalized grammar in the tradition of Head-driven Phrase Structure Grammar [15]. The grammar formalism is carefully designed to allow linguistically sophisticated analyses as well as efficient and robust processing.
In contrast to earlier work on HPSG grammar rules in Alpino are relativey detailed. However, as pointed out in [17], by organizing rules in an inheritance hierarchy, the relevant linguistic generalizations can still be captured. The Alpino grammar currently contains over 100 rules, defined in terms of a few general rule structures and principles. The grammar covers the basic constructions of Dutch (including main and subordinate clauses, (indirect) questions, imperatives, (free) relative clauses, a wide range of verbal and nominal complementation and modification patterns, and coordination) as well as a wide variety of more idiosyncratic constructions (appositions, verb-particle constructions, PP's including a particle, NP's modified by an adverb, punctuation, etc.). The lexicon contains definitions for various nominal types (nouns with various complementation patterns, proper names, pronouns, temporal nouns, deverbalized nouns), various complementizer, determiner, and adverb types, adjectives, and 36 verbal subcategorization types.
The formalism supports the use of recursive constraints over feature-structures (using delayed evaluation, [22]). This allowed us to incorporate an analysis of cross-serial dependencies based on argument-inheritance [5] and a trace-less account of extraction along the lines of [4].