On evaluation metrics in Optimality Theory
Ezer Rasin, Roni Katzir
March 2015

Our goal in this paper is to develop an evaluation metric for OT, a criterion for comparing grammars given the data. Using this criterion, the child can search through the space of possible grammars, eliminating suboptimal grammars as it proceeds. Our empirical focus is on the lexicon and the constraints, and our evaluation metric is based on the principle of Minimum Description Length (MDL). We wish to model aspects of knowledge such as the English-speaking child's knowledge that the first segment in the word 'cat' involves aspiration, that [raiDer] is underlyingly /raiter/, and that [rai:Der] is underlyingly /raider/. We take it that any theory of phonology would require this knowledge to be learned rather than innate, making this a convenient place to start. The learner we present is the first we are aware of to succeed in obtaining such knowledge. The generality of the MDL-based evaluation metric allows us to learn additional parts of the grammar without changing the learner. We demonstrate this by learning not only the lexicon and the ranking of the constraints but also the constraints themselves (both markedness and faithfulness constraints) from general schemata. In obtaining this knowledge as well, the learner is once again the first of its kind in the literature as far as we are aware.
Format: [ pdf ]
Reference: lingbuzz/001934
(please use that when you cite this article)
Published in: To appear in Linguistic Inquiry
keywords: learning, evaluation metrics, minimum description length, optimality theory, phonology
previous versions: v2 [April 2014]
v1 [September 2013]
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