Formalização da confluência para sistemas de reescrita ortogonais

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Matemática, 2012.Ortogonalidade é uma característica da programação que consiste, de uma maneira sintática, em garantir o determinismo de especificações funcionais. Essencialmente, a ortogonalidade não permite, por um lado, a ambiguidade inerente do não determinismo, isto é, a existência de diferentes regras que especificam a mesma função e que podem ser aplicadas simultaneamente (não ambiguidade) e, por outro, também proíbe a repetição de variáveis no lado esquerdo dessas regras (linearidade à esquerda). Na teoria dos Sistemas de Reescrita de Termos (TRSs), determinismo é identificado pela renomada propriedade de confluência, que basicamente a rma que sempre que houver possibilidades de simplificações ou computações diferentes de um termo, as respostas computadas ou os termos reduzidos obtidos devem coincidir. Embora a prova seja tecnicamente elaborada, confluência é bem conhecida como uma consequência da ortogonalidade. Dessa forma, ortogonalidade é uma importante característica matemática intrínseca especificação de funções recursivas, sendo naturalmente aplicada em programação e especificações funcionais. A começar pela formalização da teoria de TRSs no assistente de provas PVS, esse trabalho descreve como a confluência de TRSs ortogonais estão sendo formalizada utilizando essa ferramenta. Progressos substanciais foram constatados nessa pesquisa, obtendo-se até o presente momento formalizações completas para propriedades similares, por em com restrições, tais como a formalização completa para a propriedade de confluência de TRS's não ambíguos e lineares (à esquerda e à direita). _______________________________________________________________________________________ ABSTRACTOrthogonality is a discipline of programming that in a syntactic manner guarantees determinism of functional specifications. Essentially, orthogonality avoids, on the one side, the inherent ambiguity of non determinism, prohibiting the existence of different rules that specify the same function and that may apply simultaneously (non-ambiguity), and, on the other side, it eliminates the possibility of occurrence of repetitions of variables in the left-hand side of these rules (left linearity). In the theory of term rewriting systems (TRSs) determinism is captured by the well-known property of confluence, that basically states that whenever different computations or simplifications from a term are possible, the computed answers or the obtained reduced terms should coincide. Although the proof is technically elaborated, confluence is well-known to be a consequence of orthogonality. Thus, orthogonality is an important mathematical discipline intrinsic to the specification of recursive functions that is naturally applied in functional programming and specification. Starting from a formalization of the theory of TRSs in the proof assistant PVS, this work describes how confluence of orthogonal TRSs is being formalized in this proof assistant. Substantial progress has been done in this research, obtaining until now complete formalizations for some similar, but restricted properties, such as a complete formalization for the property of confluence of non ambiguous and (left and right) linear TRSs

Formalizing the Confluence of Orthogonal Rewriting Systems

Orthogonality is a discipline of programming that in a syntactic manner guarantees determinism of functional specifications. Essentially, orthogonality avoids, on the one side, the inherent ambiguity of non determinism, prohibiting the existence of different rules that specify the same function and that may apply simultaneously (non-ambiguity), and, on the other side, it eliminates the possibility of occurrence of repetitions of variables in the left-hand side of these rules (left linearity). In the theory of term rewriting systems (TRSs) determinism is captured by the well-known property of confluence, that basically states that whenever different computations or simplifications from a term are possible, the computed answers should coincide. Although the proofs are technically elaborated, confluence is well-known to be a consequence of orthogonality. Thus, orthogonality is an important mathematical discipline intrinsic to the specification of recursive functions that is naturally applied in functional programming and specification. Starting from a formalization of the theory of TRSs in the proof assistant PVS, this work describes how confluence of orthogonal TRSs has been formalized, based on axiomatizations of properties of rules, positions and substitutions involved in parallel steps of reduction, in this proof assistant. Proofs for some similar but restricted properties such as the property of confluence of non-ambiguous and (left and right) linear TRSs have been fully formalized.Comment: In Proceedings LSFA 2012, arXiv:1303.713

Gravidez e LES : principais riscos e complicações maternas e perinatais

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2017O lúpus eritematoso sistémico é uma doença autoimune que afeta frequentemente mulheres em idade fértil. A gravidez, apesar de não contraindicada, é considerada de risco, pois há maior probabilidade de ocorrerem complicações como perda fetal, préeclâmpsia/ eclâmpsia, rutura prematura de membranas, parto pré-termo, restrição do crescimento fetal e mortalidade perinatal. Fatores como nefrite lúpica ativa, proteinúria, presença de anticorpos antifosfolípido, suspensão da hidroxicloroquina e elevada atividade da doença no período peri-concecional, aumentam o risco de complicações. O aconselhamento pré-concecional é fundamental para uma gestação com sucesso. Situações clínicas como a síndroma de anticorpos antifosfolípido, presença de anticorpos anti-Ro/anti-La e nefrite lúpica merecem uma vigilância particular devido ao maior risco de eventos adversos.Systemic lupus erythematosus is an autoimmune disease, which often affects women in childbearing age. Pregnancy is not contra-indicated, but there is a higher risk of complications such fetal loss, preeclampsia/eclampsia, premature rupture of membranes, preterm delivery, fetal growth restriction and perinatal mortality. Factors including active lupic nephritis, the presence anti-phospholipid antibodies, discontinuation of hydroxychloroquine and activity of the disease during the periconceptional period, increase the risk of complications. Preconceptional counseling is crucial in order to obtain a successful pregnancy. Clinical situations like antiphospholipid syndrome, the presence of anti-Ro/anti-La antibodies and lupic nefritis require a particular surveillance because of the higher risk of adverse effects

A Global optimization stochastic algorithm for head motion stabilization during quadruped robot locomotion

Visually-guided locomotion is important for autonomous robotics. However, there are several di culties, for instance, the robot locomotion induces head shaking that constraints stable image acquisition and the possibility to rely on that information to act accordingly. In this work, we propose a combined approach based on a controller architecture that is able to generate locomotion for a quadruped robot and a genetic algorithm to generate head movement stabilization. The movement controllers are biologically inspired in the concept of Central Pattern Generators (CPGs) that are modelled based on nonlinear dynamical systems, coupled Hopf oscillators. This approach allows to explicitly specify parameters such as ampli- tude, o set and frequency of movement and to smoothly modulate the generated oscillations according to changes in these parameters. Thus, in order to achieve the desired head movement, opposed to the one induced by locomotion, it is necessary to appropriately tune the CPG parameters. Since this is a non-linear and non-convex optimization problem, the tuning of CPG parameters is achieved by using a global optimization method. The genetic algorithm searches for the best set of parameters that generates the head movement in order to reduce the head shaking caused by locomotion. Optimization is done o ine according to the head movement induced by the locomotion when no stabilization procedure was performed. In order to evaluate the resulting head movement, a tness function based on the Euclidian norm is investigated. Moreover, a constraint handling technique based on tournament selection was im- plemented. Experimental results on a simulated AIBO robot demonstrate that the proposed approach generates head movement that reduces signi cantly the one induced by locomotion

Locomotion gait optimization for a quadruped robot

This article describes the development of a gait optimization system that allows a fast but stable robot quadruped crawl gait. We focus in the development of a quadruped robot walking gait locomotion that combine bio-inspired Central Patterns Generators (CPGs) and Genetic Algorithms (GA). The CPGs are modelled as autonomous differential equations, that generate the necessary limb movement to perform the walking gait, and the Genetic Algorithm perform the search of the CPGs parameters. This approach allows to explicitly specify parameters such as amplitude, offset and frequency of movement and to smoothly modulate the generated trajectories according to changes in these parameters. It is therefore easy to combine the CPG with an optimization method. A genetic algorithm determines the best set of parameters that generates the limbs movements. We intend to obtain a walking gait locomotion that minimizes the vibration and maximizes the wide stability margin and the forward velocity. The experimental results, performed on a simulated Aibo robot, demonstrated that our approach allows low vibration with a high velocity and wide stability margin for a quadruped walking gait locomotion

Head motion stabilization during quadruped robot locomotion: combining CPGs and stochastic optimization methods

In this work, the authors propose a combined approach based on a controller architecture that is able to generate locomotion for a quadruped robot and a global optimization algorithm to generate head movement stabilization. The movement controllers are biologically inspired in the concept of Central Pattern Generators (CPGs) that are modelled based on nonlinear dynamical systems, coupled Hopf oscillators. This approach allows for explicitly specified parameters such as amplitude, offset and frequency of movement and to smoothly modulate the generated oscillations according to changes in these parameters. The overall idea is to generate head movement opposed to the one induced by locomotion, such that the head remains stabilized. Thus, in order to achieve this desired head movement, it is necessary to appropriately tune the CPG parameters. Three different global optimization algorithms search for this best set of parameters. In order to evaluate the resulting head movement, a fitness function based on the Euclidean norm is investigated. Moreover, a constraint-handling technique based on tournament selection was implemented

Level of Physical Activity and functional capacity of patients with pre-dialytic chronic kidney disease and in hemodialysis

O objetivo deste estudo foi comparar a capacidade funcional (CF) e o nível de atividade física (NAF) de indivíduos com doença renal crônica (DRC) em tratamento hemodialítico (HD) em longo prazo (G1); em curto prazo (G2); em tratamento conservador (G3) e indivíduos sem DRC (G4). Trata-se de um estudo transversal, descritivo, composto por uma amostra de conveniência. Foram avaliados 44 indivíduos, sendo 13 do G1 (50,6±11,5 anos), 9 do G2 (50,8±19,01), 9 do G3 (42,8±15,6) e 13 do G4 (49,2±11,2). A CF foi avaliada pelo teste de caminhada de seis minutos (TC6´), e o nível de atividade física pelo questionário IPAQ. Para a análise estatística na comparação entre grupos utilizouse o Anova One-way com post hoc de Bonferroni. Para variáveis categóricas foi utilizado o teste de qui-quadrado. Foi encontrada diferença significativa na comparação da distância percorrida no TC6’ entre G1 e G4 (409,4±108,1 x 571,9±31,5m; p=0,001) e entre G2 e G4 (422,6±133,2 x 571,9±31,5m; p=0,006). O mesmo ocorreu para valores da distância percorrida no TC6’ em percentual do previsto. Quanto ao NAF, não foram encontradas diferenças significativas entre os grupos, e a maioria dos indivíduos apresentou baixo NAF. Dessa forma, conclui-se que indivíduos com DRC que realizam HD apresentam redução da CF quando comparados a pessoas sem DRC.El objetivo de este estudio fue comparar la capacidad funcional (CF) y el nivel de actividad física (NAF) de los individuos con enfermedad renal crónica (ERC) en tratamiento de hemodiálisis (HD) a largo plazo (G1); a corto plazo (G2); en tratamiento conservador (G3) e individuos sin ERC (G4). Se trata de un estudio transversal, descriptivo, compuesto por una muestra de conveniencia. Se evaluaron 44 individuos, siendo 13 del G1 (50,6 ± 11,5 años), 9 del G2 (50,8 ± 19,01), 9 del G3 (42,8 ± 15,6), y 13 del G4 (49,2 ± 11,2). La CF fue evaluada por la prueba de caminata de seis minutos (PC6’), y el nivel de actividad física por el cuestionario IPAQ. Para el análisis estadístico en la comparación entre grupos, se utilizó el Anova One-way con prueba post-hoc de Bonferroni. Para las variables categóricas se utilizó la prueba de chi-cuadrado. Se encontró una diferencia significativa en la comparación de la distancia recorrida en el TC6’ entre G1 y G4 (409,4 ± 108,1 × 571,9 ± 31,5m; p = 0,001), y entre G2 y G4 (422,6 ± 133,2 × 571,9 ± 31,5m; p = 0,006). Lo mismo ocurrió para valores de la distancia recorrida en el TC6’ en porcentaje de lo previsto. En cuanto al NAF, no se encontraron diferencias significativas entre los grupos, y la mayoría de los individuos presentó bajo NAF. Por lo tanto, se concluye que individuos con ERC que realizan HD presentan reducción de la CF en comparación con personas sin ERC.The aim of this study was to compare the functional capacity (FC) and level of physical activity (LPA) of individuals with chronic kidney disease (CKD) in long-term hemodialysis (HD) treatment (G1); in shortterm HD treatment (G2); in conservative treatment (G3), and individuals without CKD (G4). This was a descriptive cross-sectional study with a convenience sample. A total of 44 individuals were evaluated, 13 of G1 (50.6 ± 11.5 years), 9 of G2 (50.8 ± 19.01), 9 of G3 (42.8 ± 15.6), and 13 of G4 (49 , 2 ± 11.2). FC was assessed by the six-minute walking test (6MW) and the L PA by the IPAQ questionnaire. For statistical analysis in the comparison between groups, we used ANOVA One-way with Bonferroni post hoc. For categorical variables, the Chi-square test was used. A significant difference was found in the comparison of the 6MW walking distance between G1 and G4 (409.4 ± 108.1 x 571, 9 ± 31.5m; p = 0.001) and between G2 and G4 (422.6 ± 133.2 x 571.9 ± 31.5 m, p = 0.006). Similar results were observed for 6MW distance in prediction percentage. Regarding LPA, no significant differences were found between the groups and most individuals presented low levels. Therefore, it was concluded that individuals with CKD in HD treatment present reduction of CF when compared to people without CKD

Multiobjective optimization of a quadruped robot locomotion using a genetic algorithm

In this work, it is described a gait multiobjective optimization system that allows to obtain fast but stable robot quadruped crawl gaits. We combine bioinspired Central Patterns Generators (CPGs) and Genetic Algorithms (GA). A motion architecture based on CPGs oscillators is used to model the locomotion of the robot dog and a GA is used to search parameterizations of the CPGs parameters which minimize the body vibration, maximize the velocity and maximize the wide stability margin. In this problem, there are several conflicting objectives that leads to a multiobjective formulation that is solved using the Weighted Tchebycheff scalarization method. Several experimental results show the effectiveness of this proposed approach.Fundação para a Ciência e a Tecnologia (FCT

Creating homogeneous sectors: criteria and applications of sectorization

Sectorization is the process of grouping a set of previously defined basic units (points or small areas) into a fixed number of sectors. Sectorization is also known in the literature as districting or territory design, and is usually performed to optimize one or more criteria regarding the geographic characteristics of the territory and the planning purposes of sectors. The most common criteria are equilibrium, compactness and contiguity, which can be measured in many ways. Sectorization is similar to clustering but with a different motivation. Both aggregate smaller units into groups. But, while clustering strives for inner similarity of data, sectorization aims at outer homogeneity [1]. In clustering, groups should be very different from each other, and similar points are classified in the same cluster. In sectorization, groups should be very similar to each other, and therefore very different points can be grouped in the same sector. We classify sectorization problems into four types: basic sectorization, sectorization with service centers, resectorization, and dynamic sectorization. A Decision Support System for Sectorization, D3S, is being developed to deal with these four types of problems. Multi-objective genetic algorithms were implemented in D3S using Python, and a user-friendly web interface was developed using Django. Several applications can be solved with D3S, such as political districting, sales territory design, delivery service zones, and assignment of fire stations and health services to the population.info:eu-repo/semantics/draf

Combining central pattern generators with the electromagnetism-like algorithm for head motion stabilization during quadruped robot locomotion

Visually-guided locomotion is important for autonomous robotics. However, there are several difficulties, for instance, the head shaking that results from the robot locomotion itself that constraints stable image acquisition and the possibility to rely on that information to act accordingly. In this article, we propose a controller architecture that is able to generate locomotion for a quadruped robot and to generate head motion able to minimize the head motion induced by locomotion itself. The movement controllers are biologically inspired in the concept of Central Pattern Generators (CPGs). CPGs are modelled based on nonlinear dynamical systems, coupled Hopf oscillators. This approach allows to explicitly specify parameters such as amplitude, offset and frequency of movement and to smoothly modulate the generated oscillations according to changes in these parameters. We take advantage of this particularity and propose a combined approach to generate head movement stabilization on a quadruped robot, using CPGs and a global optimization algorithm. The best set of parameters that generates the head movement are computed by the electromagnetism-like algorithm in order to reduce the head shaking caused by locomotion. Experimental results on a simulated AIBO robot demonstrate that the proposed approach generates head movement that does not eliminate but reduces the one induced by locomotion