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Title:The Proper Treatment of Optimality in Computational Phonology
Authors:Lauri Karttunen
Abstract:The Proper Treatment of Optimality in Computational Phonology

Lauri Karttunen

Xerox Research Centre Europe

This paper presents a novel formalization of optimality theory. Unlike

previous treatments of optimality in computational linguistics, starting

with Ellison (1994), the new approach does not require any explicit

marking and counting of constraint violations. It is based on the

notion of ``lenient composition'', defined as the combination of

ordinary composition and priority union. If an underlying form has

outputs that can meet a given constraint, lenient composition enforces

the constraint; if none of the output candidates meet the constraint,

lenient composition allows all of them. For the sake of greater

efficiency, we may "leniently compose" the GEN relation and all the

constraints into a single finite-state transducer that maps each

underlying form directly into its optimal surface realizations, and vice

versa, without ever producing any failing candidates. Seen from this

perspective, optimality theory is surprisingly similar to the two older

strains of finite-state phonology: classical rewrite systems and

two-level models. In particular, the ranking of optimality constraints

corresponds to the ordering of rewrite rules.

To appear in the Proceedings of FSMNLP'98. International Workshop on

Finite-state Methods in Natural Language Processing. June 29-July 1,

1998. Bilkent University, Ankara, Turkey.

Type:Paper/tech report
Article:Version 1