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Recogniton and Generation of Word Forms for Natural Language Understanding Systems: Integrating Two-Level Morphology and Feature Unification

Harald Trost
In: Applied Artificial Intelligence, Vol. 4, No. 4, Pages 411-457, Taylor & Francis, 1991.


A language-independent morphological component for the recognition and generation of word forms is presented. Based on a lexicon of morphs, the approach combines two-level morphology and a feature-based unification grammar describing word formation. To overcome the heavy use of diacritics, feature structures are associated with the two-level rules. These feature structures function as filters for the application of the rules. That way information contained in the lexicon and the morphological grammar can guide the application of the two-level rules. Moreover, information can be transmitted from the two-level part to the grammar part. This approach allows for a natural description of some nonconcatenative morphological phenomena as well as morphonological phenomena that are restricted to certain word classes in their applicability. The approach is applied to German inflectional and derivational morphology. The component may easily be incorporated into natural language understanding systems and can be especially useful in medical, scientific, or technical languages where it can be used for the automatic processing of compound words.