The Computational Complexity of Two-Level Morphology

Abstract

Morphological analysis requires knowledge of the stems, affixes, combnatory patterns, and spelling-change processes of a language. The computational difficulty of the task can be clarified by investigating the computational characteristics of specific models of morphologial processing. The use of finite-state machinery in the "two-level" model by Kimmo Koskenicimi model does not guarantee efficient processing. Reductions of the satisfiability problem show that finding the proper lexical??face correspondence in a two-level generation or recognition problem can be computationally difficult. However, another source of complexity in the existing algorithms can be sharply reduced by changing the implementation of the dictionary component. A merged dictionary with bit-vectors reduces the number of choices among alternative dictionary subdivisions by allowing several subdivisions to be searched at once.