Stephan Kepser
The paper appeared in: Proceedings AMiLP 2000
This paper provides a coalgebraic modelling of Head-Driven Phrase Structure Grammar. HPSG is a licensing theory in the sense that grammaticality is defined in terms of abstract grammar principles, well-formedness conditions on linguistic analyses rather then by a set of rules that would explicitely generate an analysis. Since coalgebras are very well suited for modelling licensing theories, we provide a conceptually particularly adequate formalisation for HPSG by showing that HPSG can indeed be modeled with coalgebras. We also show that the category of grammar models contains a final coalgebra. This final coalgebra we propose as \emph{the} model of an HPSG grammar, because it models the analyses of the structurally different readings of all and only those utterances licensed by the grammar while eliminating spurious ambiguities.