The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Renato Tinós - One of the best experts on this subject based on the ideXlab platform.
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GECCO - Enhancing partition crossover with articulation points analysis
Proceedings of the Genetic and Evolutionary Computation Conference, 2018Co-Authors: Francisco Chicano, Darrell Whitley, Gabriela Ochoa, Renato TinósAbstract:Partition Crossover is a recombination operator for pseudo-Boolean optimization with the ability to explore an exponential number of solutions in linear or square time. It decomposes the objective Function as a sum of subFunctions, each one depending on a different set of Variables. The decomposition makes it possible to select the best parent for each subFunction independently and the operator provides the best out of 2q solutions, where q is the number of sub-Functions in the decomposition. These subFunctions are defined over the connected components of the recombination graph: a subgraph of the objective Function Variable interaction graph containing only the differing Variables in the two parents. In this paper, we advance further and propose a new way to increase the number of linearly independent subFunctions by analyzing the articulation points of the recombination graph. These points correspond to Variables that, once flipped, increase the number of connected components. The presence of a connected component with an articulation point increases the number of explored solutions by a factor of, at least, 4. We evaluate the new operator using Iterated Local Search combined with Partition Crossover to solve NK Landscapes and MAX-SAT.
Steven Shea - One of the best experts on this subject based on the ideXlab platform.
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endogenous circadian rhythm of pulmonary Function in healthy humans
American Journal of Respiratory and Critical Care Medicine, 2000Co-Authors: Christina M Spengler, Steven SheaAbstract:Numerous studies have demonstrated a diurnal rhythm in indices of pulmonary Function in both healthy subjects and subjects with asthma, with minima occurring during the night. To determine whether such diurnal changes are caused by an endogenous circadian rhythm or by diurnal alterations in behavior or the environment, we measured indices of pulmonary Function throughout a “constant routine” protocol designed to unmask underlying circadian rhythms. After two acclimation days in the laboratory, 10 healthy adults maintained relaxed wakefulness in a semirecumbent posture in a constant environment with low light (10 lux) for 41 h. Measurements of FEV 1 , FEVC, PEF, blood cortisol, and core body temperature (CBT) were performed every 2 h. Results of cosinor analysis of group data aligned to CBT circadian minimum revealed significant circadian variations in FEV 1 and FEV 1 /FEVC, cortisol, and CBT, and lack of significant circadian variations in FEVC and PEF. The ranges (peak to trough) of mean circadian changes in spirometric Variables were 2.0‐3.2% of the mesor. The circadian minima of all Variables occurred within the usual sleep period (although subjects remained awake). Because of differences in phase relationships between CBT and pulmonary Function among subjects, the circadian rhythms within subjects were generally larger than the group average circadian changes, being significant for FEV 1 /FEVC in 5 of 10 subjects and for PEF in 6 of 10 subjects. Sleep deprivation (24 h) failed to cause a significant change in any pulmonary Function Variable (when controlled for circadian phase). Thus, endogenous circadian rhythms contribute to diurnal changes in pulmonary Function in healthy subjects. Numerous studies have demonstrated a diurnal rhythm in indices of pulmonary Function. The clearest examples of this phenomenon are the existence of patients with asthma who experience a nocturnal worsening of pulmonary Function, asthmatic symptoms, and sleep quality, and the observation of a diurnal variation in the death rate among patients with asthma with the peak occurring during the early morning hours (e.g., [1‐11]). However, such studies were not able to determine whether these diurnal variations are caused by an endogenous circadian rhythm (related to the output of the circadian pacemaker), diurnal alterations in behavior (e.g., activity, meals, posture, or sleep) or diurnal alterations in the environment (e.g., temperature, light, or allergen exposure). To try and separate effects of sleep from effects of circadian rhythms, some studies have used total sleep deprivation,
Francisco Chicano - One of the best experts on this subject based on the ideXlab platform.
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GECCO - Enhancing partition crossover with articulation points analysis
Proceedings of the Genetic and Evolutionary Computation Conference, 2018Co-Authors: Francisco Chicano, Darrell Whitley, Gabriela Ochoa, Renato TinósAbstract:Partition Crossover is a recombination operator for pseudo-Boolean optimization with the ability to explore an exponential number of solutions in linear or square time. It decomposes the objective Function as a sum of subFunctions, each one depending on a different set of Variables. The decomposition makes it possible to select the best parent for each subFunction independently and the operator provides the best out of 2q solutions, where q is the number of sub-Functions in the decomposition. These subFunctions are defined over the connected components of the recombination graph: a subgraph of the objective Function Variable interaction graph containing only the differing Variables in the two parents. In this paper, we advance further and propose a new way to increase the number of linearly independent subFunctions by analyzing the articulation points of the recombination graph. These points correspond to Variables that, once flipped, increase the number of connected components. The presence of a connected component with an articulation point increases the number of explored solutions by a factor of, at least, 4. We evaluate the new operator using Iterated Local Search combined with Partition Crossover to solve NK Landscapes and MAX-SAT.
Yasuaki Oishi - One of the best experts on this subject based on the ideXlab platform.
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An Asymptotically Exact Approach to Robust Semidefinite Programming Problems with Function Variables
IEEE Transactions on Automatic Control, 2009Co-Authors: Yasuaki OishiAbstract:This technical note provides an approximate approach to a semidefinite programming problem with a parameter-dependent constraint and a Function Variable. This problem covers a variety of control problems including a robust stability/performance analysis with a parameter-dependent Lyapunov Function. In the proposed approach, the original problem is approximated by a standard semidefinite programming problem through two steps: first, the Function Variable is approximated by a finite-dimensional Variable; second, the parameter-dependent constraint is approximated by a finite number of parameter-independent constraints. Both steps produce approximation error. On the sum of these approximation errors, this technical note provides an upper bound. This bound enables quantitative analysis of the approach and gives an efficient way to reduction of the approximation error. Moreover, this technical note discusses how to verify that an optimal solution of the approximate problem is actually optimal also for the original problem.
Bjarne Steensgaard - One of the best experts on this subject based on the ideXlab platform.
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points to analysis in almost linear time
Symposium on Principles of Programming Languages, 1996Co-Authors: Bjarne SteensgaardAbstract:We present an interprocedural flow-insensitive points-to analysis based on type inference methods with an almost linear time cost complexity To our knowledge, this is the asymptotically fastest non-trivial interprocedural points-to analysis algorithm yet described The algorithm is based on a non-standard type system. The type inferred for any Variable represents a set of locations and includes a type which in turn represents a set of locations possibly pointed to by the Variable. The type inferred for a Function Variable represents a set of Functions It may point to and includes a type signature for these Functions The results are equivalent to those of a flow-insensitive alias analysis (and control flow analysis) that assumes alias relations are reflexive and transitive.This work makes three contributions. The first is a type system for describing a universally valid storage shape graph for a program in linear space. The second is a constraint system which often leads to better results than the "obvious" constraint system for the given type system The third is an almost linear time algorithm for points-to analysis by solving a constraint system.
