On the Use of Second Order Neighbors to Escape from Local Optima

Designing efficient local search based algorithms requires to consider the specific properties of the problems. We introduce a simple and effi- cient strategy, the Extended Reach, that escapes from local optima ob- tained from a best improvement local search and apply it to the linear ordering problem (LOP), the traveling salesperson problem (TSP) and the quadratic assignment problem (QAP). This strategy is based on two landscape properties observed in the literature. First, it considers that a local optimum is usually located in the frontier of its own attraction basin, and thus, it is enough to inspect the second order neighbors to reach a (better) solution inside an attraction basin of a better local optimum. Second, taking into account that for the LOP and specific neighborhoods it is possible to discard solutions without the need of being evaluated, we extend this result to the TSP with the 2-opt neighborhood to avoid the unnecessary evaluation of solutions. Efficient ways of evaluating the second order neighbors are also presented, based on the cost differences, reducing significantly the computation cost. Experimental results on ran- dom and benchmark instances show that our strategy, indeed, escapes from local optima despite its simplicity.PID2019-104966GB-I00 AXA Research Fun

Cuestionario para la selección de conceptos fundamentales: análisis de validez y confiabilidad

La conceptualización tiene una importancia capital en el aprendizaje, cuya medición se puede representar como una modificación de las estructuras cognitivas del individuo. Para su análisis resulta esencial establecer los conceptos objetivos y comprobar la estabilidad o modificación de sus relaciones. Este estudio describe la creación de un instrumento de recogida de información, concretamente un cuestionario, validado por expertos en la materia, donde se permite a los alumnos introducir los conceptos más importantes sobre una temática concreta, para su posterior análisis con técnicas de representación de la estructura cognitiva. Es un instrumento de recolección de información abierto, en cuanto a que se ajusta a las necesidades de los investigadores, y, a su vez, orientado, ya que permite establecer las líneas fundamentales que relacionan los conceptos sobre los que se cuestiona

Statistical methods applied to composition studies of ultrahigh energy cosmic rays

The mass composition of high energy cosmic rays above $10^{17}$ eV is a crucial issue to solve some open questions in astrophysics such as the acceleration and propagation mechanisms. Unfortunately, the standard procedures to identify the primary particle of a cosmic ray shower have low efficiency mainly due to large fluctuations and limited experimental observables. We present a statistical method for composition studies based on several measurable features of the longitudinal development of the CR shower such as $N_{max}$, $X_{max}$, asymmetry, skewness and kurtosis. Principal component analysis (PCA) was used to evaluate the relevance of each parameter in the representation of the overall shower features and a linear discriminant analysis (LDA) was used to combine the different parameters to maximize the discrimination between different particle showers. The new parameter from LDA provides a separation between primary gammas, proton and iron nuclei better than the procedures based on $X_{max}$ only. The method proposed here was successfully tested in the energy range from $10^{17}$ to $10^{20}$ eV even when limitations of shower track length were included in order to simulate the field of view of fluorescence telescopes

Reglas constitutivas y racionalidad normativa en la teoría de los hechos institucionales de John Searle

En este artículo nos proponemos examinar los supuestos teóricos generales de la ontología social desarrollada por el filósofo norteamericano John Searle. Para ello, expondremos los elementos esenciales de su teoría de las instituciones, a fin de mostrar cómo para el pensador anglosajón las realidades sociales surgen de determinados actos de habla (speech acts), haciendo hincapié en el rol especial que en ello cumplen el lenguaje y lo que Searle denomina como intencionalidad colectiva (collective intentionality). Esta exposición nos permitirá poner de manifiesto una cierta insuficiencia en una aproximación de esta clase, mostrando la conveniencia, no prevista por Searle, de hacer de la racionalidad (y específicamente de la racionalidad práctica) la fuente última de toda posible normatividad. Con ello, estaremos en condiciones de asumir los desarrollos de una de las más innovadoras teorías sociales del último siglo, para así reconducirlos o reinterpretarlos a la luz de las doctrinas más clásicas sobre la vida en sociedad y el orden moral

Vortex density models for superconductivity and superfluidity

We study some functionals that describe the density of vortex lines in superconductors subject to an applied magnetic field, and in Bose-Einstein condensates subject to rotational forcing, in quite general domains in 3 dimensions. These functionals are derived from more basic models via Gamma-convergence, here and in a companion paper. In our main results, we use these functionals to obtain descriptions of the critical applied magnetic field (for superconductors) and forcing (for Bose-Einstein), above which ground states exhibit nontrivial vorticity, as well as a characterization of the vortex density in terms of a non local vector-valued generalization of the classical obstacle problem.Comment: 34 page