Optimality theory (Prince and Smolensky ) abandons rewrite rules. Rules are replaced by two new concepts: (1) a universal function called GEN and (2) a set of ranked universal constraints. GEN provides each input form with a (possibly infinite) set of output candidates. The constraints eliminate all but the best output candidate. Because many constraints are in conflict, it may be impossible for any candidate to satisfy all of them. The winner is determined by taking into consideration the language-specific ranking of the constraints. The winning candidate is the one with the least serious violations.
In order to explore the computational aspects of the theory it is useful to focus on a concrete example, even simpler than the Yokuts vowel alternation we just discussed. We will take the familiar case of syllabification constraints discussed by Prince and Smolensky  and many subsequent authors (Ellison , Tesar , Hammond ).