A Constraint on Variables in Phonology

Two kinds of variables have been used in generative phonology: ABBREVIATORY VARIABLES, which have only one expansion in the application of a given rule to a string; and ESSENTIAL VARIABLES, which have many values simultaneously, e.g. the 'star notation' of SPE. Essential variables can be dispensed with entirely if rules are allowed to apply iteratively rather than simultaneously. Abbreviatory variables can be severely constrained by the RELEVANCY CONDITION proposed here, which allows only IRRELEVANT material to intervene between the FOCUS and DETERMINANT of a rule. The result is a more highly constrained and more explanatory theory of phonology.