This paper presents a novel forrealization of optimality theory. Unlike pre- yions 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; ff none of the output candidates meets the constraint, lenient composition allows all of them. For the sake of greater efficiency, we may "eniently compose" the a. relation and all the constraints into a single finite-state transducer that maps each underlying form directly into its op- timal surface realizations, and vice versa.. 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.

Eisner's (1997a) Primitive Optimality Theory is a simple formal model of a subset of Optimality Theory (Prince and Smolensky 1993). The work presented here implements this model and extends it. The implementation is used to evaluate the Primitive Optimality Theory model, and is in itself a useful tool for linguistic analysis. The model is evaluated in terms of its success or failure as an attempt to formulate a cognitively plausible, computationally tractable, and mathematically formal model of the Optimality Theoretic framework of phonological theory. As part of this evaluation, a comprehensive, implemented analysis is given for the harmony and disharmony phenomena of Turkish. In addition to an evaluation of the Primitive Optimality Theory model, concrete proposals are suggested for possible extensions to the model, and for improved models that, unlike Primitive Optimality Theory, can model non-concatenative morphology, Paradigm Uniformity, and reduplication.

Abstract not found

We develop an extensible description logic for stating the content of optimalitytheoretic constraints in phonology, and specify a class of structures for interpreting it. The aim is a transparent formalisation of OT. We show how to state a wide range of constraints, including markedness, input–output faithfulness and base–reduplicant faithfulness. However, output–output correspondence and ‘intercandidate’ sympathy are revealed to be problematic: it is unclear that any reasonable class of structures can reconstruct their proponents’ intentions. But our contribution is positive. Proponents of both output–output correspondence and sympathy have offered alternatives that fit into the general OT picture. We show how to state these in a reasonable extension of our formalism. The problematic constraint types were developed to deal with opaque phenomena. We hope to shed new light on the debate about how to handle opacity, by subjecting some common responses to it within OT to critical investigation.

This paper proposes an expansion of set of prim- itive constraints available within the Primitive Optimality Theory framework (Eisner, 1997a). This expansion consists of the addition of a new family of constraints--existential implicational constraints, which allow the specification of faithfulness constraints that can be satisfied at a distance--and the definition of two ways to combine simple constraints into com plax constraints, that is, constraint disjunction (Crowhurst and Hewitt, 1995) and local constra. int conjunction (Smolensky, 1995).

Primitive Optimality Theory (OTP) (Eisner, 1997a; Albro, 1998), a computational model of Optimality Theory (Prince and Smolensky, 1993), employs a finite state machine to represent the set of active candidates at each stage of an Optimality Theoretic derivation, as well as weighted finite state machines to represent the constraints themselves. For some purposes, however, it would be convenient if the set of candidates were limited by some set of criteria capable of being described only in a higher-level grammar formalism, such as a Context Free Grammar, a Context Sensitive Grammar, or a Multiple Context Free Grammar (Seki et al., 1991). Examples include reduplication and phrasal stress models. Here we introduce a mechanism for OTP-like Optimality Theory in which the constraints remain weighted finite state machines, but sets of candidates are represented by higher-level grammars. In particular, we use multiple context-free grammars to model reduplication in the manner of Correspondence Theory (McCarthy and Prince, 1995), and develop an extended version of the Earley Algorithm (Earley, 1970) to apply the constraints to a reduplicating candidate set.

This paper presents a previously unnoticed universal property of stress patterns in the world’s languages: they are, for small neighborhoods, neighborhood-distinct. Neighborhood-distinctness is a locality condition defined in automata-theoretic terms. This universal is established by examining stress patterns contained in two typological studies, Bailey (1995) and Gordon (2002). Strikingly, many logically possible— but unattested—patterns do not have this property. Not only does neighborhood-distinctness unite the attested patterns in a non-trivial way, it also naturally provides an inductive principle allowing learners to generalise from limited data. A learning algorithm is presented which generalises by failing to distinguish same-neighborhood environments perceived in the learner’s linguistic input—hence learning neighborhood-distinct patterns—as well as almost every stress pattern in the typology. In this way, this work lends support to the idea that properties of the learner can explain certain properties of the attested typology, an idea not straightforwardly available in Optimality-theoretic and Principle and Parameter frameworks.

Recent work in metrical typology within Optimality Theory has emphasised the rhythmic distribution of stress peaks by reference to clashes and lapses, compared to the more central role of foot constituency characteristic of most previous approaches. One consequence of this emphasis has been the introduction of constraints that require reference to non-adjacent objects in the representation, such as two unstressed syllables plus a word edge or a stress peak. I argue here for a constraint-based approach to metrical typology that permits only strictly local formulations. This approach requires increased reference to foot structure, while maintaining local reference to clashes and lapses. The revised set of constraints predicts a larger set of possible stress systems, but correctly includes an attested iambic pattern excluded by recent theories.

Abstract not found

1993, 2004) is ‘‘in general computationally intractable’ ’ on the basis of a proof adapted from Eisner 1997a. We take issue with this conclusion on two grounds. First, the intractability result holds only in cases where the constraint set is not fixed in advance (contra usual definitions of OT), and second, the result crucially depends on a particular representation of OT grammars. We show that there is an alternative representation of OT grammars that allows for efficient computation of optimal surface forms and provides deeper insight into the sources of complexity of OT. We conclude that it is a mistake to reject OT on the grounds that it is computationally intractable.