A framework for transferring one linguistic representation into another, e.g. transferring an underlying form into a surface form. Before Prince & Smolensky (1993), phonologists tended to this with a sequentially ordered set of rules, each of which transferred a representation into another. With OT (that's the abbreviation), there are no intermediate steps in the derivation, but a set of ranked constraints chooses the optimal output form from a set of candidates.
In Praat, you can draw Optimality-Theoretic tableaus and simulate Optimality-Theoretic learning. See the OT learning tutorial.
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