EBL2: An Approach To Automatic Lexical Acquisition

A method for automatic lexical acquisition is outlined. An existing lexicon that, in addition to ordinary lexical entries, contains prototypical entries for various non-exclusive paradigms of open-class words, is extended by inferring new lexical entries from texts containing unknown words. This is done by comparing the constraints placed on the unknown words by the natural language system's grammar with the prototypes and a number of hand-coded phrase templates specific for each paradigm. Once a sufficient number of observations of the word in different contexts have been made, a lexical entry is constructed for the word by assigning it to one or several paradigm(s).Parsing sentences with unknown words is normally very time-consuming due to the large number of grammatically possible analyses. To circumvent this problem, other phrase templates are extracted automatically from the grammar and domain-specific texts using an explanation-based learning method. These templates represent grammatically correct sentence patterns. When a sentence matches a template, the original parsing component can be bypassed, reducing parsing times dramatically.

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