Results 1  10
of
27
A TabuSearch Hyperheuristic for Timetabling and Rostering
, 2003
"... Hyperheuristics can be defined to be heuristics which choose between heuristics in order to solve a given optimisation problem. The main motivation behind the development of such approaches is the goal of developing automated scheduling methods which are not restricted to one problem. In this paper ..."
Abstract

Cited by 117 (56 self)
 Add to MetaCart
Hyperheuristics can be defined to be heuristics which choose between heuristics in order to solve a given optimisation problem. The main motivation behind the development of such approaches is the goal of developing automated scheduling methods which are not restricted to one problem. In this paper we report the investigation of a hyperheuristic approach and evaluate it on various instances of two distinct timetabling and rostering problems. In the framework of our hyperheuristic approach, heuristics compete using rules based on the principles of reinforcement learning. A tabu list of heuristics is also maintained which prevents certain heuristics from being chosen at certain times during the search. We demonstrate that this tabusearch hyperheuristic is an easily reusable method which can produce solutions of at least acceptable quality across a variety of problems and instances. In effect the proposed method is capable of producing solutions that are competitive with those obtained using stateof theart problemspecific techniques for the problems studied here, but is fundamentally more general than those techniques.
Applications to timetabling
 Handbook of Graph Theory, chapter 5.6
, 2004
"... Abstract Automating the neighbourhood selection process in an iterative approach that uses multiple heuristics is not a trivial task. Hyperheuristics are search methodologies that not only aim to provide a general framework for solving problem instances at different difficulty levels in a given dom ..."
Abstract

Cited by 29 (17 self)
 Add to MetaCart
Abstract Automating the neighbourhood selection process in an iterative approach that uses multiple heuristics is not a trivial task. Hyperheuristics are search methodologies that not only aim to provide a general framework for solving problem instances at different difficulty levels in a given domain, but a key goal is also to extend the level of generality so that different problems from different domains can also be solved. Indeed, a major challenge is to explore how the heuristic design process might be automated. Almost all existing iterative selection hyperheuristics performing single point search contain two successive stages; heuristic selection and move acceptance. Different operators can be used in either of the stages. Recent studies explore ways of introducing learning mechanisms into the search process for improving the performance of hyperheuristics. In this study, a broad empirical analysis is performed comparing Monte Carlo based hyperheuristics for solving capacitated examination timetabling problems. One of these hyperheuristics is an approach that overlaps two stages and presents them in a single algorithmic body. A learning heuristic selection method (L) operates in harmony with a simulated annealing move acceptance method using reheating (SA) based on some shared variables. Yet, the heuristic selection and move
Exploring Hyperheuristic Methodologies with Genetic Programming
"... Hyperheuristics represent a novel search methodology that is motivated by the goal of automating the process of selecting or combining simpler heuristics in order to solve hard computational search problems. An extension of the original hyperheuristic idea is to generate new heuristics which are n ..."
Abstract

Cited by 20 (11 self)
 Add to MetaCart
Hyperheuristics represent a novel search methodology that is motivated by the goal of automating the process of selecting or combining simpler heuristics in order to solve hard computational search problems. An extension of the original hyperheuristic idea is to generate new heuristics which are not currently known. These approaches operate on a search space of heuristics rather than directly on a search space of solutions to the underlying problem which is the case with most metaheuristics implementations. In the majority of hyperheuristic studies so far, a framework is provided with a set of human designed heuristics, taken from the literature, and with good measures of performance in practice. A less well studied approach aims to generate new heuristics from a set of potential heuristic components. The purpose of this chapter is to discuss this class of hyperheuristics, in which Genetic Programming is the most widely used methodology. A detailed discussion is presented including the steps needed to apply this technique, some representative case studies, a literature review of related work, and a discussion of relevant issues. Our aim is to convey the exciting potential of this innovative approach for automating the heuristic design process
A Classification of Hyperheuristic Approaches
"... The current state of the art in hyperheuristic research comprises a set of approaches that share the common goal of automating the design and adaptation of heuristic methods to solve hard computational search problems. The main goal is to produce more generally applicable search methodologies. In ..."
Abstract

Cited by 18 (13 self)
 Add to MetaCart
The current state of the art in hyperheuristic research comprises a set of approaches that share the common goal of automating the design and adaptation of heuristic methods to solve hard computational search problems. The main goal is to produce more generally applicable search methodologies. In this chapter we present and overview of previous categorisations of hyperheuristics and provide a unified classification and definition which captures the work that is being undertaken in this field. We distinguish between two main hyperheuristic categories: heuristic selection and heuristic generation. Some representative examples of each category are discussed in detail. Our goal is to both clarify the main features of existing techniques and to suggest new directions for hyperheuristic research.
Random search for hyperparameter optimization
 In: Journal of Machine Learning Research
"... Grid search and manual search are the most widely used strategies for hyperparameter optimization. This paper shows empirically and theoretically that randomly chosen trials are more efficient for hyperparameter optimization than trials on a grid. Empirical evidence comes from a comparison with a ..."
Abstract

Cited by 17 (1 self)
 Add to MetaCart
Grid search and manual search are the most widely used strategies for hyperparameter optimization. This paper shows empirically and theoretically that randomly chosen trials are more efficient for hyperparameter optimization than trials on a grid. Empirical evidence comes from a comparison with a large previous study that used grid search and manual search to configure neural networks and deep belief networks. Compared with neural networks configured by a pure grid search, we find that random search over the same domain is able to find models that are as good or better within a small fraction of the computation time. Granting random search the same computational budget, random search finds better models by effectively searching a larger, less promising configuration space. Compared with deep belief networks configured by a thoughtful combination of manual search and grid search, purely random search over the same 32dimensional configuration space found statistically equal performance on four of seven data sets, and superior performance on one of seven. A Gaussian process analysis of the function from hyperparameters to validation set performance reveals that for most data sets only a few of the hyperparameters really matter, but that different hyperparameters are important on different data sets. This phenomenon makes
Investigation of a Tabu Assisted HyperHeuristic Genetic Algorithm
 In proceedings of Congress on Evolutionary Computation(CEC2003
, 2003
"... AbstractThis paper investigates a tabu assisted genetic algorithm based hyperheuristic (hyperTGA) for personnel scheduling problems. We recently introduced a hyperheuristic genetic algorithm (hyperGA) with an adaptive length chromosome which aims to evolve an ordering of lowlevel heuristics in ..."
Abstract

Cited by 15 (4 self)
 Add to MetaCart
AbstractThis paper investigates a tabu assisted genetic algorithm based hyperheuristic (hyperTGA) for personnel scheduling problems. We recently introduced a hyperheuristic genetic algorithm (hyperGA) with an adaptive length chromosome which aims to evolve an ordering of lowlevel heuristics in order to find good quality solutions to given problems. The addition of a tabu method, the focus of this paper, extends that work. The aim of adding a tabu list to the hyperGA is to indicate the efficiency of each gene within the chromosome. We apply the algorithm to a geographically distributed training staff and course scheduling problem and compare the computational results with our previous hyperGA. 1.
A simulated annealing hyperheuristic methodology for flexible decision support
, 2007
"... One of the main motivations for investigating hyperheuristic methodologies is to provide a more general search framework than is currently available. Most of the current search techniques represent approaches that are largely adapted for specific search problems (and, in some cases, even specific ..."
Abstract

Cited by 14 (7 self)
 Add to MetaCart
One of the main motivations for investigating hyperheuristic methodologies is to provide a more general search framework than is currently available. Most of the current search techniques represent approaches that are largely adapted for specific search problems (and, in some cases, even specific problem instances). There are many realworld scenarios where the development of such bespoke systems is entirely appropriate. However, there are other situations where it would be beneficial to have methodologies which are more generally applicable to more problems. One of our motivating goals is to underpin the development of more flexible search methodologies that can be easily and automatically employed on a broader range of problems than is currently possible. Almost all the heuristics that have appeared in the literature have been designed and selected by humans. In this paper, we investigate a simulated annealing hyperheuristic methodology which operates on a search space of heuristics and which employs a stochastic heuristic selection strategy and a shortterm memory. The generality and performance of the proposed algorithm is demonstrated over a large number of benchmark data sets drawn from three very different and difficult (NPhard) problems: nurse rostering, university course timetabling and onedimensional bin packing. Experimental results show that the proposed hyperheuristic is able to achieve significant performance improvements over a recently proposed tabu search hyperheuristic without lowering the level of generality. We
An Adaptive Length Chromosome Hyperheuristic Genetic Algorithm for a Trainer Scheduling Problem
 Proceedings of the fourth AsiaPacific Conference on Simulated Evolution And Learning, (SEAL'02), Orchid Country Club, Singapore, 1822 Nov 2002
"... HyperGA was introduced by the authors as a genetic algorithm based hyperheuristic which aims to evolve an ordering of lowlevel heuristics so as to find a good quality solution to a given problem. The adaptive length chromosome hyperGA, let's call it ALChyperGA, is an extension of the authors pre ..."
Abstract

Cited by 13 (4 self)
 Add to MetaCart
HyperGA was introduced by the authors as a genetic algorithm based hyperheuristic which aims to evolve an ordering of lowlevel heuristics so as to find a good quality solution to a given problem. The adaptive length chromosome hyperGA, let's call it ALChyperGA, is an extension of the authors previous work, in which the chromosome was of fixed length. The aim of a variable length chromosome is two fold; 1) it allows dynamic removal and insertion of heuristics 2) it allows the GA to find a good chromosome length which could otherwise only be found by experimentation. We apply the ALChyperGA to a geographically distributed training staff and courses scheduling problem, and report that good quality solution can be found. We also present results for four versions of the ALChyperGA, applied to five test data sets.
Local search with very largescale neighborhoods for optimal permutations in machine translation
 In Proc. of the Workshop on Computationally Hard Problems and Joint Inference
, 2006
"... We introduce a novel decoding procedure for statistical machine translation and other ordering tasks based on a family of Very LargeScale Neighborhoods, some of which have previously been applied to other NPhard permutation problems. We significantly generalize these problems by simultaneously con ..."
Abstract

Cited by 12 (3 self)
 Add to MetaCart
We introduce a novel decoding procedure for statistical machine translation and other ordering tasks based on a family of Very LargeScale Neighborhoods, some of which have previously been applied to other NPhard permutation problems. We significantly generalize these problems by simultaneously considering three distinct sets of ordering costs. We discuss how these costs might apply to MT, and some possibilities for training them. We show how to search and sample from exponentially large neighborhoods using efficient dynamic programming algorithms that resemble statistical parsing. We also incorporate techniques from statistical parsing to improve the runtime of our search. Finally, we report results of preliminary experiments indicating that the approach holds promise. 1
Heuristic selection for stochastic search optimization: Modeling solution quality by extreme value theory
 In Proceedings of the 10th International Conference on Principles and Practice of Constraint Programming
, 2004
"... Abstract. The success of stochastic algorithms is often due to their ability to effectively amplify the performance of search heuristics. This is certainly the case with stochastic sampling algorithms such as heuristicbiased stochastic sampling (HBSS) and valuebiased stochastic sampling (VBSS), wh ..."
Abstract

Cited by 12 (5 self)
 Add to MetaCart
Abstract. The success of stochastic algorithms is often due to their ability to effectively amplify the performance of search heuristics. This is certainly the case with stochastic sampling algorithms such as heuristicbiased stochastic sampling (HBSS) and valuebiased stochastic sampling (VBSS), wherein a heuristic is used to bias a stochastic policy for choosing among alternative branches in the search tree. One complication in getting the most out of algorithms like HBSS and VBSS in a given problem domain is the need to identify the most effective search heuristic. In many domains, the relative performance of various heuristics tends to vary across different problem instances and no single heuristic dominates. In such cases, the choice of any given heuristic will be limiting and it would be advantageous to gain the collective power of several heuristics. Toward this goal, this paper describes a framework for integrating multiple heuristics within a stochastic sampling search algorithm. In its essence, the framework uses onlinegenerated statistical models of the search performance of different base heuristics to select which to employ on each subsequent iteration of the search. To estimate the solution quality distribution resulting from repeated application of a strong heuristic within a stochastic search, we propose the use of models from extreme value theory (EVT). Our EVTmotivated approach is validated on the NPHard problem of resourceconstrained project scheduling with time windows (RCPSP/max). Using VBSS as a base stochastic sampling algorithm, the integrated use of a set of project scheduling heuristics is shown to be competitive with the current best known heuristic algorithm for RCPSP/max and in some cases even improves upon best known solutions to difficult benchmark instances. 1