Digraph Analysis Of Dictionary Preposition Definitions

We develop a model of preposition definitions in a machine-readable dictionary using the theory of labeled directed graphs and analyze the resulting digraphs to determine a primitive set of preposition senses. We characterize these primitives and show how they can be used to develop an inheritance hierarchy for prepositions, representing the definitions by a type and slots for its arguments. By analyzing the definitions, we develop criteria for disambiguating among the highly polysemous primitives. We show how these criteria can be used in developing the inheritance hierarchy and how they may be used in assigning theta roles to the objects of transitive verbs. Finally, we describe the use of the disambiguation criteria to parse and represent the meaning of the prepositions as used in encyclopedia articles.