Estudio comparativo de estrategias heurísticas de generación de soluciones para el problema de asignación de exámenes

Timetabling se refiere a un conjunto de problemas de optimización combinatoria, que intentan asignar recursos, sean aulas, docentes o intervalos de tiempo para distintas necesidades de estudiantes, cursos y exámenes. En el presente trabajo se aborda una de las variantes de este problema que busca agendar exámenes a distintos intervalos de tiempo, cumpliendo con las restricciones de que ningún alumno debe asistir a más de un examen en el mismo momento y, en la medida de lo posible, que tenga el mayor tiempo libre entre las evaluaciones. La cantidad de combinaciones a considerar para una instancia tamaño moderado hacen inviable la búsqueda de la solución óptima, debido al tiempo que demandaría encontrarla. En consecuencia, en este artículo se utilizan distintas estrategias para combinar heurísticas que permiten obtener una buena solución al problema en un intervalo de tiempo reducido. Las heurísticas mencionadas fueron probadas sobre un conjunto de instancias estándar de manera individual así como también combinadas de manera secuencial yjerárquica. En las pruebas realizadas se obtuvieron mejores resultados mediante el método jerárquico. Debido a lo anterior es posible afirmar la superioridad de este último método sobre los demás utilizados en el presente trabajo

An Efficient Mining Approach for Handling Web Access Sequences

The World Wide Web (WWW) becomes an important source for collecting, storing, and sharing the information. Based on the users query the traditional web page search approximately retrieves the related link and some of the search engines are Alta, Vista, Google, etc. The process of web mining defines to determine the unknown and useful information from web data. Web mining contains the two approaches such as data-based approach and process-based approach. Now a day the data-based approach is the widely used approach. It is used to extract the knowledge from web data in the form of hyper link, and web log data. In this study, the modern technique is presented for mining web access utility-based tree construction under Modified Genetic Algorithm (MGA). MGA tree are newly created to deploy the tree construction. In the web access sequences tree construction for the most part relies upon internal and external utility values. The performance of the proposed technique provides an efficient Web access sequences for both static and incremental data. Furthermore, this research work is helpful for both forward references and backward references of web access sequences

Solving Examination Timetabling Problem using Partial Exam Assignment with Great Deluge Algorithm

Constructing a quality solution for the examination timetable problem is a difficult task. This paper presents a partial exam assignment approach with great deluge algorithm as the improvement mechanism in order to generate good quality timetable. In this approach, exams are ordered based on graph heuristics and only selected exams (partial exams) are scheduled first and then improved using great deluge algorithm. The entire process continues until all of the exams have been scheduled. We implement the proposed technique on the Toronto benchmark datasets. Experimental results indicate that in all problem instances, this proposed method outperforms traditional great deluge algorithm and when comparing with the state-of-the-art approaches, our approach produces competitive solution for all instances, with some cases outperform other reported result

The Application of Late Acceptance Heuristic Method for the Tanzanian High School Timetabling Problem

High School timetabling is the problem of scheduling lessons of different subjects and teachers to timeslots within a week, while satisfying a set of constraints which are classified into hard and soft constraints. This problem is different from university course timetabling problem because of the differences in structures including classroom allocations and grouping of subject combinations. Given the scarce education resources in developing countries, high school timetabling problem plays a very important role in optimizing the use of meager resources and therefore contribute to improvement of quality of education. The problem has attracted attention of many researchers around the world; however, very little has been done in Tanzania. This paper presents a solution algorithm known as Late Acceptance heuristic for the problem and compares results with previous work on Simulated Annealing and Great Deluge Algorithm for three schools in Dar es Salaam Tanzania. It is concluded that Late Acceptance heuristic gives results which are similar to the previous two algorithms but performs better in terms of time saving. Keywords: Late Acceptance; High School Timetabling; Combinatorial Optimization; Heuristics; NP-Har

Fuzzy adaptive parameter control of a late acceptance hyper-heuristic

A traditional iterative selection hyper-heuristic which manages a set of low level heuristics relies on two core components, a method for selecting a heuristic to apply at a given point, and a method to decide whether or not to accept the result of the heuristic application. In this paper, we present an initial study of a fuzzy system to control the list-size parameter of late- acceptance move acceptance method as a selection hyper-heuristic component. The performance of the fuzzy controlled selection hyper-heuristic is compared to its fixed parameter version and the best hyper-heuristic from a competition on the MAX-SAT problem domain. The results illustrate that a fuzzy control system can potentially be effective within a hyper-heuristic improving its performance

Problemas de optimización combinatoria: una propuesta que combina algoritmos genéticos y metaheurísticas

Timetabling se refiere al conjunto de problemas de optimización combinatoria que intentan asignar recursos, sean aulas, docentes o intervalos de tiempo, para distintas necesidades de estudiantes, cursos y exámenes. El presente trabajo se ocupa de una de las variantes de este problema, que busca agendar exámenes a distintos intervalos de tiempo, cumpliendo con las restricciones de que ningún alumno debe asistir a más de un examen en el mismo momento y que, en la medida de lo posible, tenga el mayor tiempo libre entre las evaluaciones. Los intervalos de tiempo no tienen restricciones en cuanto a la cantidad de exámenes que puedan asignárseles. Como estrategia de resolución se utiliza un algoritmo genético, que combina diversas heurísticas para la construcción de soluciones factibles que conforman la población inicial con la que trabaja el algoritmo. Dichas heurísticas fueron seleccionadas priorizando la calidad de la solución construida. También se definieron operadores de cruzamiento y mutación particulares, con el objetivo de mejorar la calidad de la solución resultante del proceso genético o, al menos, evitar la generación de soluciones no factibles. Mediante el algoritmo propuesto se alcanzaron soluciones relativamente buenas con pocas evaluaciones de la función objetivo y en un tiempo de ejecución razonable

Hybrid feature selection method based on particle swarm optimization and adaptive local search method

Machine learning has been expansively examined with data classification as the most popularly researched subject. The accurateness of prediction is impacted by the data provided to the classification algorithm. Meanwhile, utilizing a large amount of data may incur costs especially in data collection and preprocessing. Studies on feature selection were mainly to establish techniques that can decrease the number of utilized features (attributes) in classification, also using data that generate accurate prediction is important. Hence, a particle swarm optimization (PSO) algorithm is suggested in the current article for selecting the ideal set of features. PSO algorithm showed to be superior in different domains in exploring the search space and local search algorithms are good in exploiting the search regions. Thus, we propose the hybridized PSO algorithm with an adaptive local search technique which works based on the current PSO search state and used for accepting the candidate solution. Having this combination balances the local intensification as well as the global diversification of the searching process. Hence, the suggested algorithm surpasses the original PSO algorithm and other comparable approaches, in terms of performance

Tuning a Simulated Annealing metaheuristic for cross-domain search

Simulated Annealing is a well known local search metaheuristic used for solving computationally hard optimization problems. Cross-domain search poses a higher level issue where a single solution method is used with minor, preferably no modification for solving characteristically different optimisation problems. The performance of a metaheuristic is often dependant on its initial parameter settings, hence detecting the best configuration, i.e. parameter tuning is crucial, which becomes a further challenge for cross-domain search. In this paper, we investigate the cross-domain search performance of Simulated Annealing via tuning for solving six problems, ranging from personnel scheduling to vehicle routing under a stochastic local search framework. The empirical results show that Simulated Annealing is extremely sensitive to the initial parameter settings leading to sub-standard performance when used as a single solution method for cross-domain search. Moreover, we demonstrate that cross-domain parameter tuning is inferior to domain-level tuning highlighting the requirements for adaptive parameter configurations when dealing with cross-domain search

Markov Chain Selection Hyper-heuristic for the Optimisation of Constrained Magic Squares

UKCI 2015: UK Workshop on Computational Intelligence, University of Exeter, UK, 7-9 September 2015A square matrix of size n × n, containing each of the numbers (1, . . . , n2) in which every row, column and both diagonals has the same total is referred to as a magic square. The problem can be formulated as an optimisation problem where the task is to minimise the deviation from the magic square constraints and is tackled here by using hyper-heuristics. Hyper-heuristics have recently attracted the attention of the artificial intelligence, operations research, engineering and computer science communities where the aim is to design and develop high level strategies as general solvers which are applicable to a range of different problem domains. There are two main types of hyper-heuristics in the literature: methodologies to select and to generate heuristics and both types of approaches search the space of heuristics rather than solutions. In this study, we describe a Markov chain selection hyper-heuristic as an effective solution methodology for optimising constrained magic squares. The empirical results show that the proposed hyper-heuristic is able to outperform the current state-of-the-art method