972 resultados para sequent calculus


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Quantum Lie algebras are generalizations of Lie algebras which have the quantum parameter h built into their structure. They have been defined concretely as certain submodules L-h(g) of the quantized enveloping algebras U-h(g). On them the quantum Lie product is given by the quantum adjoint action. Here we define for any finite-dimensional simple complex Lie algebra g an abstract quantum Lie algebra g(h) independent of any concrete realization. Its h-dependent structure constants are given in terms of inverse quantum Clebsch-Gordan coefficients. We then show that all concrete quantum Lie algebras L-h(g) are isomorphic to an abstract quantum Lie algebra g(h). In this way we prove two important properties of quantum Lie algebras: 1) all quantum Lie algebras L-h(g) associated to the same g are isomorphic, 2) the quantum Lie product of any Ch(B) is q-antisymmetric. We also describe a construction of L-h(g) which establishes their existence.

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A program can be refined either by transforming the whole program or by refining one of its components. The refinement of a component is, for the main part, independent of the remainder of the program. However, refinement of a component can depend on the context of the component for information about the variables that are in scope and what their types are. The refinement can also take advantage of additional information, such as any precondition the component can assume. The aim of this paper is to introduce a technique, which we call program window inference, to handle such contextual information during derivations in the refinement calculus. The idea is borrowed from a technique, called window inference, for handling context in theorem proving. Window inference is the primary proof paradigm of the Ergo proof editor. This tool has been extended to mechanize refinement using program window inference. (C) 1997 Elsevier Science B.V.

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In this paper we demonstrate a refinement calculus for logic programs, which is a framework for developing logic programs from specifications. The paper is written in a tutorial-style, using a running example to illustrate how the refinement calculus is used to develop logic programs. The paper also presents an overview of some of the advanced features of the calculus, including the introduction of higher-order procedures and the refinement of abstract data types.

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Background: The aim of this study was to assess the prevalence, extent, and severity of clinical attachment loss (CAL) and to investigate the association of demographic, socioeconomic, and behavioral risk indicators with CAL in an untreated isolated population in Brazil. Methods: All subjects aged >= 12 years were identified by a census. Participants were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured, written questionnaire. Results: Among the 214 subjects who were interviewed and examined clinically, CAL >= 5 mm in at least one site was observed in 8% of the 12- to 19-year-olds and in all dentate subjects >= 50 years of age; the age-dependent prevalence of CAL >= 7 mm in at least one site ranged from 5% among 12- to 19-year-olds to 83% among subjects >= 50 years old. Multivariate analysis identified plaque (odds ratio [OR] = 2.8), supragingival calculus (OR = 2.9 to 10.6), age >= 30 years (OR = 11.4), and smoking (OR = 2.4) as risk indicators for CAL >= 5 mm and smoking (OR = 8.2) as a risk indicator for CAL >= 7 mm. Conclusions: CAL is highly prevalent in this isolated population. The high occurrence of CAL in young age groups and the confirmation of traditional risk indicators for CAL in this study suggest that other factors, such as host susceptibility, may be needed to explain the high levels of CAL found. Age and behavioral factors were risk indicators associated significantly with the CAL found in this population and may be useful indicators of high-risk subjects for periodontal diseases.

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P>Aim The aim of this study was to investigate the possible associations between isolated growth hormone deficiency (IGHD) and periodontal attachment loss (PAL) in adults affected by congenital IGHD. Materials and methods Forty-five previously identified IGHD subjects were eligible for this study. The final study sample comprised 32 cases (gender:20M/12F; age:44.8 +/- 17.5) matched for age, gender, diabetes, smoking status and income to 32 controls (non-IGHD subjects). Participants were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured, written questionnaire. Periodontitis was defined as proximal PAL >= 5 mm affecting >= 30% of teeth. Results No significant differences were observed in the percentage of sites with visible plaque between IGHD and non-IGHD subjects (59.4% versus 46.9%, p=0.32). IGHD subjects had significant less supragingival calculus (31.3% versus 59.4%, p=0.02) and more bleeding on probing (71.9% versus 18.8%, p < 0.01) than controls. PAL >= 5 mm was significantly more prevalent (100% versus 71.9%, p < 0.01) and affected more teeth (30.5% versus 6.7%, p < 0.01) in cases than in controls. After adjusting for supragingival calculus, IGHD cases had a higher likelihood of having periodontitis than controls (OR=17.4-17.8, 95% CI=2.3-134.9, p=0.004-0.005). Conclusion Congenital IGHD subjects have a greater chance of having PAL.

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Background: The aim of this study was to assess the prevalence, extent, and severity of probing depth (PD) and to investigate the associations between demographic, socioeconomic, and behavioral risk indicators and PD in a periodontally untreated and isolated population in Brazil. Methods: The target population consisted of all individuals aged >= 12 years as identified by a census. Consenting participants were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured written questionnaire. Results: Among the 214 subjects who were interviewed and clinically examined, PD >= 4 mm was observed in 54% to 83% of the subjects, depending on age, whereas the age-dependent prevalence of PD :6 mm ranged from 5% among 12- to 19-year-olds to 50% among 40- to 49-year-olds, decreasing to 40% among subjects >= 50 years of age. Multivariate analyses identified supragingival calculus (odds ratio [OR] = 5.4 to 10.3; 95% confidence intervals [CIs]: 2.5 to 11.6 and 4.0 to 26.2 for 20% to 50% and > 50% of the sites, respectively) as a risk indicator for PD A mm, whereas age :40 years (OR = 9.0; 95% CI: 1.7 to 48.5), being a moderate/heavy smoker (OR = 3.7; 95% CI: 1.4 to 10. 1), and having supragingival calculus in 20% to 50% of sites (OR = 6.8; 95% CI: 1.4 to 32.4) or in >50% of sites (OR = 15.3; 95% CI: 3.2 to 73.6) were risk indicators for PD >= 6 mm. Having undergone urgency dental treatment was a protective factor for PD A and >= 6 mm (OR = 0.4; 95% CI: 0.2 to 0.8). Conclusions: Increased PD is highly prevalent in this isolated population. Behavioral factors played a significant role as risk indicators for increased PD in this isolated population.

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The purpose of this study was to evaluate the characteristics of diseased root surfaces treated by the association of scaling and the application of Carisolv. Twenty-four uniradicular periodontally involved teeth were used in this study The teeth were divided randomly into three groups: eight teeth were scaled and root planed until there was a complete visible removal of calculus (group 1), Carisolv was applied on the root surfaces of eight teeth twice for 30 seconds before scaling with a sharp curette (group 2), and eight teeth received the same treatment as in group 2 but with a blunt curette (group 3). Specimens were examined using scanning electron microscopy The superficial aspect of the roots from group 1 presented scratches that mirrored the curette cutting edge, and the smear layer completely covered the surface. Root surfaces from groups 2 and 3 also presented a smear layer that covered the surface completely but it was somewhat smoother than group 1. The use of Carisolv as an adjunct to scaling and root planing presented no advantage for smear layer removal over scaling alone, suggesting that no benefit is obtained by the use of Carisolv during periodontal mechanical treatment. (Int J Periodontics Restorative Dent 2011;31:91-95.)

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Introduction: In this double-blind and randomized controlled trial, we analyzed whether a lower concentration of chlorhexidine in dentifrices could reduce the risk of tooth staining without compromising its effectiveness in controlling gingivitis, bleeding, and dental plaque. Methods: Volunteers with fixed orthodontic appliances were randomly divided into 3 groups: control, 1100 ppm F, NaF (n = 27); experimental, chlorhexidine 0.50% (n = 27); and experimental, chlorhexidine 0.75% (n = 27). At baseline, and after 6 and 12 weeks, clinical examinations were carried out. Staining, calculus, gingivitis, bleeding, and dental plaque data were analyzed with Friedman tests to evaluate intragroup changes over time. To detect intergroup differences after 12 months, the data were evaluated with Kruskal-Wallis tests. Dunn tests were used in both situations for necessary post-hoc analyses. Results: The groups were statistically similar for the stain, calculus, and plaque indexes, but there were statistically significant differences for the gingival and bleeding indexes. During the experimental periods, gingivitis and bleeding scores improved in all 3 groups. Only the 0.75% chlorhexidine dentifrice significantly increased the stain index, although most patients did not notice the stains. The intergroup comparison showed a statistically significant better performance of the experimental groups regarding the gingival and bleeding indexes. Conclusions: This study suggests that the use of dentifrices with lower concentration of chlorhexidine can reduce the risk of tooth staining without compromising its effectiveness in controlling gingivitis and bleeding in orthodontic patients. (Am J Orthod Dentofacial Orthop 2009; 136: 651-6)

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Program compilation can be formally defined as a sequence of equivalence-preserving transformations, or refinements, from high-level language programs to assembler code, Recent models also incorporate timing properties, but the resulting formalisms are intimidatingly complex. Here we take advantage of a new, simple model of real-time refinement, based on predicate transformer semantics, to present a straightforward compilation formalism that incorporates real-time constraints. (C) 2002 Elsevier Science B.V. All rights reserved.

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The refinement calculus is a well-established theory for deriving program code from specifications. Recent research has extended the theory to handle timing requirements, as well as functional ones, and we have developed an interactive programming tool based on these extensions. Through a number of case studies completed using the tool, this paper explains how the tool helps the programmer by supporting the many forms of variables needed in the theory. These include simple state variables as in the untimed calculus, trace variables that model the evolution of properties over time, auxiliary variables that exist only to support formal reasoning, subroutine parameters, and variables shared between parallel processes.

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A adoção da ação afirmativa denominada cotas nas universidades federais - reserva de vagas para estudantes que tenham cursado integralmente o ensino médio em escolas públicas - continua sendo polêmica, mesmo após a sanção da Lei nº.12.711 de 2012, o que torna oportuna a contribuição aos estudos a respeito da utilização desse sistema nas universidades públicas brasileiras. Este trabalho teve por objetivo estudar o desempenho acadêmico de alunos cotistas do Centro de Ciências Jurídicas e Econômicas e do Centro Tecnológico da Universidade Federal do Espírito Santo – UFES, no período de 2008 a 2013, considerando as duas entradas anuais nos referidos cursos. O presente estudo analisou o aproveitamento acadêmico dos alunos de 15 cursos de graduação ofertados pelos Centros nominados buscando saber em quais cursos e disciplinas existem diferenças significativas de desempenho, a partir do coeficiente de rendimento acadêmico (CRA) e da média final das disciplinas cursadas por alunos cotistas e não cotistas, visando a propor ações institucionais para a redução dessas diferenças. Na pesquisa, de caráter quantitativo, utilizou-se o método estatístico de análise de variância ANOVA. A partir das análises realizadas foi possível inferir a existência de diferenças de rendimento nos cursos de engenharia,principalmente em disciplinas de cálculo e álgebra. O curso de Direito, por sua vez, apresentou diferença significativa de desempenho, não obstante as médias não estarem abaixo do índice necessário para a aprovação. Quando a comparação é feita considerando o sexo, verificou-se no curso de Ciências Econômicas e Ciências da Computação uma disparidade significativa de rendimento em favor dos alunos do sexo feminino cotistas em detrimento dos não cotistas do mesmo sexo.

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Periodontal disease (PD) is widely known among veterinarians for its high prevalence and serious consequences to the dogs. The objective of this study was to assess the occurrence of PD in dogs that live in the micro-region of Viçosa, treated at the Veterinary Hospital of the Federal University of Viçosa (HVT - Hospital Veterinário da Universidade Federal de Viçosa), as well as to assess how aware of this disease dog owners are. In order to do so, all dogs treated at the HVT from March 10th, 2009 to November 30th, 2009, on alternate days, had their oral cavities examined. Medical history data, such as age, type of food, main complaint and owner consent, halitosis, presence of dental calculus, inflammation and gingival recession and tooth loss, were collected. A prevalence of 88.67% was found for PD in dogs referred to the HVT, and 2.67% were referred due to this disease. Of all the owners who participated in the study, 43.83% knew about periodontal disease and of these 17.46% made use of some type of prevention or treatment. Therefore, periodontal disease is highly prevalent and the owners are not aware of the disease. Thus, a dog owner clarification program on periodontal disease is needed in the area where HVT-UFV operates.

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In practical applications of optimization it is common to have several conflicting objective functions to optimize. Frequently, these functions are subject to noise or can be of black-box type, preventing the use of derivative-based techniques. We propose a novel multiobjective derivative-free methodology, calling it direct multisearch (DMS), which does not aggregate any of the objective functions. Our framework is inspired by the search/poll paradigm of direct-search methods of directional type and uses the concept of Pareto dominance to maintain a list of nondominated points (from which the new iterates or poll centers are chosen). The aim of our method is to generate as many points in the Pareto front as possible from the polling procedure itself, while keeping the whole framework general enough to accommodate other disseminating strategies, in particular, when using the (here also) optional search step. DMS generalizes to multiobjective optimization (MOO) all direct-search methods of directional type. We prove under the common assumptions used in direct search for single objective optimization that at least one limit point of the sequence of iterates generated by DMS lies in (a stationary form of) the Pareto front. However, extensive computational experience has shown that our methodology has an impressive capability of generating the whole Pareto front, even without using a search step. Two by-products of this paper are (i) the development of a collection of test problems for MOO and (ii) the extension of performance and data profiles to MOO, allowing a comparison of several solvers on a large set of test problems, in terms of their efficiency and robustness to determine Pareto fronts.

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Deoxyribonucleic acid, or DNA, is the most fundamental aspect of life but present day scientific knowledge has merely scratched the surface of the problem posed by its decoding. While experimental methods provide insightful clues, the adoption of analysis tools supported by the formalism of mathematics will lead to a systematic and solid build-up of knowledge. This paper studies human DNA from the perspective of system dynamics. By associating entropy and the Fourier transform, several global properties of the code are revealed. The fractional order characteristics emerge as a natural consequence of the information content. These properties constitute a small piece of scientific knowledge that will support further efforts towards the final aim of establishing a comprehensive theory of the phenomena involved in life.