Similarity and phonotactics in Arabic

The statistical patterns of language are systematic linguistic data which must be accounted for in linguistic theory. The phonotactics of the Arabic verbal roots are presented as a case study. In Arabic, the acceptability of a verbal root is gradiently dependent on the similarity of homorganic consonant pairs within the root. We propose the stochastic constraint model of phonological patterning, in which the relative frequency of a phonological form provides a measure of its acceptability. The stochastic constraint model can be parameterized to account for gradient or categorical constraints. We also propose a novel similarity metric for phonological segments based on the representational framework of structured specification. Structured specification provides a basis for a similarity metric for phonemes that is sensitive to featural redundancy and contrastiveness. This metric is superior to previous proposals using underspecification. The account of Arabic consonant cooccurrence using similarity and the stochastic constraint provides a more accurate account of the data than the non-quantitative autosegmental account, demonstrating that a quantitative description is necessary to capture the true pattern of the data.