11 - LKB Encoding of Lexical Knowledge

Summary

Introduction In setting up a lexical component for natural language processing systems, one finds that a considerable amount of information is often repeated across sets of word entries. To make the task of grammar writing more efficient, shared information can be expressed in the form of partially specified templates and distributed to relevant entries by inheritance. Shared information across sets of partially specified templates can be factored out and conveyed using the same technique. This makes it possible to avoid redefining the same information structures, thus reducing a great deal of redundancy in the specification of word forms. For example, general properties of intransitive verbs concerning subcategorization and argument structure can be simply stated once, and then inherited by lexical entries which provide word specific information, e.g. orthography, predicate sense, aktionsart, selectional restrictions. Likewise, properties which are common to all verbs (e.g. part of speech, presence of a subject) or subsets of the verb class (presence of a direct object for transitive and ditransitive verbs) can be defined as templates which subsume all members of the verb class or some subset of it. This approach to word specification provides a highly structured organization of the lexicon according to which the properties of related word types as well as the relation between word types and specific word forms are expressed in terms of structure sharing and inheritance (Flickinger, Pollard and Wasow, 1985; Flickinger, 1987; Pollard and Sag, 1987, pp. 191–209).