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Optimality Theory (optimality + theory)
Selected AbstractsWhat Is Optimality Theory?1LINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 4 2007John J. McCarthy Optimality Theory is a general model of how grammars are structured. This article surveys the motivations for Optimality Theory, its core principles, and the basics of analysis. It also addresses some frequently asked questions about this theory and offers suggestions for further reading. [source] Weighted Constraints in Generative LinguisticsCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 6 2009Joe Pater Abstract Harmonic Grammar (HG) and Optimality Theory (OT) are closely related formal frameworks for the study of language. In both, the structure of a given language is determined by the relative strengths of a set of constraints. They differ in how these strengths are represented: as numerical weights (HG) or as ranks (OT). Weighted constraints have advantages for the construction of accounts of language learning and other cognitive processes, partly because they allow for the adaptation of connectionist and statistical models. HG has been little studied in generative linguistics, however, largely due to influential claims that weighted constraints make incorrect predictions about the typology of natural languages, predictions that are not shared by the more popular OT. This paper makes the case that HG is in fact a promising framework for typological research, and reviews and extends the existing arguments for weighted over ranked constraints. [source] Early Child Grammars: Qualitative and Quantitative Analysis of Morphosyntactic ProductionCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 5 2006Géraldine Legendre Abstract This article reports on a series of 5 analyses of spontaneous production of verbal inflection (tense and person,number agreement) by 2-year-olds acquiring French as a native language. A formal analysis of the qualitative and quantitative results is developed using the unique resources of Optimality Theory (OT; Prince & Smolensky, 2004). It is argued that acquisition of morphosyntax proceeds via overlapping grammars (rather than through abrupt changes), which OT formalizes in terms of partial rather than total constraint rankings. Initially, economy of structure constraints take priority over faithfulness constraints that demand faithful expression of a speaker's intent, resulting in child production of tense that is comparable in level to that of child-directed speech. Using the independent Predominant Length of Utterance measure of syntactic development proposed in Vainikka, Legendre, and Todorova (1999), production of agreement is shown first to lag behind tense then to compete with tense at an intermediate stage of development. As the child's development progresses, faithfulness constraints become more dominant, and the overall production of tense and agreement becomes adult-like. [source] How do small browsers respond to resource changes?FUNCTIONAL ECOLOGY, Issue 3 2010Dietary response of the Cape grysbok to clearing alien Acacias Summary 1.,The responses of small ruminants to changing food availability may vary from a broadening of the diet with declining availability, as predicted by optimality theory, to the maintenance of a restricted, selected diet, as predicted by the body-size constraint hypothesis. 2.,We test these conflicting predictions by assessing the dietary responses of the Cape grysbok Raphicerus melanotis, a near-endemic to the Cape Floristic region, South Africa, to changes in the availability of a key forage species (i.e. Australian Acacia sp.). We predicted that the removal of alien Acacias would cause a broadening of the diet, and the consumption of previously avoided species, despite the selectivity imposed by their small body size. We used faecal analyses to describe grysbok diet and assessed diet quality through faecal quality analyses. 3.,Results show that grysbok are highly selective browsers, able to change their diet and dietary preferences in response to changes in food availability. Animals included additional species in the diet in the absence of alien Acacias, altered their principal dietary items, broadened foraging strategies to include grass and some previously avoided species became preferred in the absence of Acacias. These dietary changes were effective in maintaining dietary protein intake, and caused a reduction in fibre intake in the absence of Acacias. 4.,The data do not support the body size constraint hypothesis which is thought to impose a limit on the ability of small ruminants to select additional dietary species. 5.,These data represent the first quantification of extensive grazing (up to 51% of the diet) by a species considered a browser. These findings support the prediction of optimality theory, whereby animals faced with a loss of important food items broaden their diet to include previously avoided species. [source] The importance of growth and mortality costs in the evolution of the optimal life historyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2006D. A. ROFF Abstract A central assumption of life history theory is that the evolution of the component traits is determined in part by trade-offs between these traits. Whereas the existence of such trade-offs has been well demonstrated, the relative importance of these remains unclear. In this paper we use optimality theory to test the hypothesis that the trade-off between present and future fecundity induced by the costs of continued growth is a sufficient explanation for the optimal age at first reproduction, ,, and the optimal allocation to reproduction, G, in 38 populations of perch and Arctic char. This hypothesis is rejected for both traits and we conclude that this trade-off, by itself, is an insufficient explanation for the observed values of , and G. Similarly, a fitness function that assumes a mortality cost to reproduction but no growth cost cannot account for the observed values of ,. In contrast, under the assumption that fitness is maximized, the observed life histories can be accounted for by the joint action of trade-offs between growth and reproductive allocation and between mortality and reproductive allocation (Individual Juvenile Mortality model). Although the ability of the growth/mortality model to fit the data does not prove that this is the mechanism driving the evolution of the optimal age at first reproduction and allocation to reproduction, the fit does demonstrate that the hypothesis is consistent with the data and hence cannot at this time be rejected. We also examine two simpler versions of this model, one in which adult mortality is a constant proportion of juvenile mortality [Proportional Juvenile Mortality (PJM) model] and one in which the proportionality is constant within but not necessarily between species [Specific Juvenile Mortality (SSJM) model]. We find that the PJM model is unacceptable but that the SSJM model produces fits suggesting that, within the two species studied, juvenile mortality is proportional to adult mortality but the value differs between the two species. [source] Tradeoffs and sexual conflict over women's fertility preferences in MpimbweAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2009Monique Borgerhoff Mulder There are two principle evolutionary models for why women reduce their fertility, which can be used to explain the modern demographic transition. The first derives from optimality theory (specifically the "quantity-quality" tradeoff hypothesis), and the second from models of biased cultural transmission ("prestige bias" and "kin influence" hypotheses). Data on family planning preferences collected in 1996 and 1998 in a rural African village (in Mpimbwe, Tanzania) are used to test predictions derived from each hypothesis and show that both "quantity-quality" tradeoffs and biased cultural transmission underlie Pimbwe women's decisions. Reproductive decisions, however, are not made in a vacuum. Men and women's ideal family sizes often differ, and sexual conflict is particularly likely to affect a woman's success in limiting her family size. Pimbwe women's reproductive output between the initial family planning survey in 1996 and the most recent demographic survey (2006) is analyzed in relation to both the woman's preferences to limit her family and her exposure to husbands and husbands' kin. Despite wide differences in desired family sizes between men and women the extent of sexual conflict in this population is restricted to husbands and wives, and affects not a woman's use or planned use of modern contraception but her success in employing such methods effectively. There is also some evidence that a woman's mother and her kin assist in the use and effective use of modern methods, offering a prevailing force to the high-fertility objectives of the husband. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] Using the Optimal Robust Receiver Operating Characteristic (ROC) Curve for Predictive Genetic TestsBIOMETRICS, Issue 2 2010Qing Lu Summary Current ongoing genome-wide association (GWA) studies represent a powerful approach to uncover common unknown genetic variants causing common complex diseases. The discovery of these genetic variants offers an important opportunity for early disease prediction, prevention, and individualized treatment. We describe here a method of combining multiple genetic variants for early disease prediction, based on the optimality theory of the likelihood ratio (LR). Such theory simply shows that the receiver operating characteristic (ROC) curve based on the LR has maximum performance at each cutoff point and that the area under the ROC curve so obtained is highest among that of all approaches. Through simulations and a real data application, we compared it with the commonly used logistic regression and classification tree approaches. The three approaches show similar performance if we know the underlying disease model. However, for most common diseases we have little prior knowledge of the disease model and in this situation the new method has an advantage over logistic regression and classification tree approaches. We applied the new method to the type 1 diabetes GWA data from the Wellcome Trust Case Control Consortium. Based on five single nucleotide polymorphisms, the test reaches medium level classification accuracy. With more genetic findings to be discovered in the future, we believe a predictive genetic test for type 1 diabetes can be successfully constructed and eventually implemented for clinical use. [source] Harmony in Linguistic CognitionCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 5 2006Paul Smolensky Abstract In this article, I survey the integrated connectionist/symbolic (ICS) cognitive architecture in which higher cognition must be formally characterized on two levels of description. At the microlevel, parallel distributed processing (PDP) characterizes mental processing; this PDP system has special organization in virtue of which it can be characterized at the macrolevel as a kind of symbolic computational system. The symbolic system inherits certain properties from its PDP substrate; the symbolic functions computed constitute optimization of a well-formedness measure called Harmony. The most important outgrowth of the ICS research program is optimality theory (Prince & Smolensky, 1993/2004), an optimization-based grammatical theory that provides a formal theory of cross-linguistic typology. Linguistically, Harmony maximization corresponds to minimization of markedness or structural ill-formedness. Cognitive explanation in ICS requires the collaboration of symbolic and connectionist principles. ICS is developed in detail in Smolensky and Legendre (2006a); this article is a précis of and guide to those volumes. [source] | ||||||||||