Mixed categories in HPSG

It is often assumed that there is a small number of primitive, universal, and perhaps innate syntactic categories. Mixed category constructions involve lexical items that seem to be central members of more that one part of speech and so pose a problem for the standard view of syntactic categories. For example, the verbal gerund phrase in Chris worried about Pat’s frequently eating hamburgers has some internal properties of a VP but the external distribution of an NP. The verbal gerund eating has both verbal and nominal properties. It combines with a direct object and an adverb, but it also combines with possessor and occurs as the object of a preposition. This paper presents an HPSG analysis of English verbal gerunds based on a more fine-grained theory of syntactic categories. A category like ‘noun’ is actually a bundle of recurring grammatical information represented as constraints on types in the hierarchical lexicon. Mixed categories have an atypical combination of information. For example, the verbal gerund shares the distributional properties of nouns and the selectional properties of verbs, but is not a member of either category per se. Since under this view different dimensions of grammatical information can, in principle, vary independently, the behavior of mixed categories creates no paradox.