Results 1  10
of
25
A MAXMIN Ant System for the University Course Timetabling Problem
 in Proceedings of the 3rd International Workshop on Ant Algorithm, ANTS 2002, Lecture Notes in Computer Science
, 2002
"... We consider a simplification of a typical university course timetabling problem involving three types of hard and three types of soft constraints. A MAXMIN Ant System, which makes use of a separate local search routine, is proposed for tackling this problem. We devise an appropriate construction gr ..."
Abstract

Cited by 33 (0 self)
 Add to MetaCart
We consider a simplification of a typical university course timetabling problem involving three types of hard and three types of soft constraints. A MAXMIN Ant System, which makes use of a separate local search routine, is proposed for tackling this problem. We devise an appropriate construction graph and pheromone matrix representation after considering alternatives. The resulting algorithm is tested over a set of eleven instances from three classes of the problem. The results demonstrate that the ant system is able to construct significantly better timetables than an algorithm that iterates the local search procedure from random starting solutions.
Heuristics for the Mirrored Traveling Tournament Problem
 European Journal of Operational Research
, 2004
"... Professional sports leagues are a major economic activity around the world. Teams and leagues do not want to waste their investments in players and structure in consequence of poor schedules of games. ..."
Abstract

Cited by 20 (3 self)
 Add to MetaCart
Professional sports leagues are a major economic activity around the world. Teams and leagues do not want to waste their investments in players and structure in consequence of poor schedules of games.
A TimePredefined Approach to Course Timetabling
, 2003
"... A common weakness of local search metaheuristics, such as Simulated Annealing, in solving combinatorial optimisation problems, is the necessity of setting a certain number of parameters. This tends to make significantly increase the total amount of time required to solve the problem and often requir ..."
Abstract

Cited by 14 (5 self)
 Add to MetaCart
A common weakness of local search metaheuristics, such as Simulated Annealing, in solving combinatorial optimisation problems, is the necessity of setting a certain number of parameters. This tends to make significantly increase the total amount of time required to solve the problem and often requires a high level of experience from the user. This paper is motivated by the goal of overcoming this drawback by employing "parameterfree" techniques in the context of automatically solving course timetabling problems.
Multipleretrieval CaseBased Reasoning for course timetabling problems
 Journal of Operations Research Society
, 2005
"... This paper presents amultipleretriev6 approach that partitions a large problem into smallsolvS40 subproblems byrecursiv5/ inputting theunsolv/ part of the graph into the decision tree for retrievSW The adaptation combines theretriev4 partial solutions of all the partitioned subproblems ..."
Abstract

Cited by 12 (9 self)
 Add to MetaCart
This paper presents amultipleretriev6 approach that partitions a large problem into smallsolvS40 subproblems byrecursiv5/ inputting theunsolv/ part of the graph into the decision tree for retrievSW The adaptation combines theretriev4 partial solutions of all the partitioned subproblems and employs a graph heuristic method to construct the whole solution for the new case. We present a methodology which is not dependent upon problemspecific information and which, as such, represents an approach which underpins the goal of building more general timetabling systems. We also explore the question of whether this multipleretriev CBR could be aneffectiv initialization method for local search methods such as hill climbing, tabu search and simulated annealing. Significant results are obtained from a wide range of experiments. An ev56qA9SW of the CBR system is presented and the impact of the approach on timetabling research is discussed. We see that the approach does indeed represent aneffectiv initialization method for these approaches
Annealed MAP
"... Maximum a Posteriori assignment (MAP) is the problem of finding the most probable instantiation of a set of variables given the partial evidence on the other variables in a Bayesian network. MAP has been shown to be a NPhard problem [22], even for constrained networks, such as polytrees [18]. ..."
Abstract

Cited by 9 (0 self)
 Add to MetaCart
Maximum a Posteriori assignment (MAP) is the problem of finding the most probable instantiation of a set of variables given the partial evidence on the other variables in a Bayesian network. MAP has been shown to be a NPhard problem [22], even for constrained networks, such as polytrees [18].
An Advanced Model and Novel Metaheuristic Solution Methods to Personnel Scheduling in Healthcare
"... Constructing timetables of work for personnel in healthcare institutions is known to be a highly constrained and di#cult problem to solve. In this thesis, we introduce a model for the practical rostering problem in Belgian hospitals. It is general enough to cope with the large set of constraints and ..."
Abstract

Cited by 7 (0 self)
 Add to MetaCart
Constructing timetables of work for personnel in healthcare institutions is known to be a highly constrained and di#cult problem to solve. In this thesis, we introduce a model for the practical rostering problem in Belgian hospitals. It is general enough to cope with the large set of constraints and to meet varying objectives encountered in practice.
CaseBased Initialisation of Metaheuristics for Examination Timetabling
 Proc. of 1st Multidisciplinary International Conference on Scheduling: Theory and Applications (MISTA 2003
, 2003
"... Examination timetabling problems are traditionally solved by choosing a solution scheme from a plethora of heuristic algorithms based either on direct construction principle or direct construction followed by some incremental improvement procedure. A number of hybrid approaches have also been examin ..."
Abstract

Cited by 6 (2 self)
 Add to MetaCart
Examination timetabling problems are traditionally solved by choosing a solution scheme from a plethora of heuristic algorithms based either on direct construction principle or direct construction followed by some incremental improvement procedure. A number of hybrid approaches have also been examined in which a sequential heuristic and a metaheuristic are employed successively. As a rule, best results for a problem instance are obtained by implementing heuristics with domain specific knowledge. However, solutions of this kind are not easily adoptable across different problem classes. To mitigate the need for a problemspecificknowledgebased approach we developed a solution scheme by incorporating case based reasoning methodology. This scheme constructs a solution to a given problem by implementing case based reasoning to select a sequential heuristic, which produces a good initial solution for Great Deluge metaheuristic. By generating a series of computational experiments on benchmark problems we demonstrate that this solution approach gives comparable or better results than solutions generated by stateoftheart approaches based on single Great Deluge Algorithm.
Location area planning and celltoswitch assignment in cellular networks
 IEEE Transactions on Wireless Communications
, 2004
"... Abstract—Location area (LA) planning plays an important role in cellular networks because of the tradeoff caused by paging and registration signalling. The upper boundary for the size of an LA is the service area of a mobile services switching center (MSC). In that extreme case, the cost of paging i ..."
Abstract

Cited by 5 (0 self)
 Add to MetaCart
Abstract—Location area (LA) planning plays an important role in cellular networks because of the tradeoff caused by paging and registration signalling. The upper boundary for the size of an LA is the service area of a mobile services switching center (MSC). In that extreme case, the cost of paging is at its maximum but no registration is needed. On the other hand, if each cell is an LA, the paging cost is minimal but the cost of registration is the largest. Between these extremes lie one or more partitions of the MSC service area that minimize the total cost of paging and registration. In this paper, we seek to determine the location areas in an optimum fashion. Cell to switch assignments are also determined to achieve the minimization of the network cost. For that purpose, we use the available network information to formulate a realistic optimization problem, and propose an algorithm based on simulated annealing (SA) for its solution. Then, we investigate the quality of the SAbased technique by comparing it to greedy search, random generation methods, and a heuristic algorithm. Index Terms—Location area (LA), location management, location tracking, location update, paging area, simulated annealing. I.
A generic objectoriented constraintbased model for university course timetabling
 THE PRACTICE AND THEORY OF AUTOMATED TIMETABLING: SELECTED PAPERS FROM THE THIRD INTERNATIONAL CONFERENCE, 28 – 47. LECTURE NOTES IN COMPUTER SCIENCE
, 2001
"... The construction of course timetables for academic institutions is a very difficult problem with a lot of constraints that have to be respected and a huge search space to be explored, even if the size of the problem input is not significantly large, due to the exponential number of the possible fe ..."
Abstract

Cited by 5 (0 self)
 Add to MetaCart
The construction of course timetables for academic institutions is a very difficult problem with a lot of constraints that have to be respected and a huge search space to be explored, even if the size of the problem input is not significantly large, due to the exponential number of the possible feasible timetables. On the other hand, the problem itself does not have a widely approved definition, since different variations of it are faced by different departments. However, there exists a set of entities and constraints among them which are common to every possible instantiation of the timetabling problem. In this paper, we present a model of this common core in terms of Ilog Solver, a constraint programming objectoriented C++ library, and we show the way this model may be extended to cover the needs of a specific academic unit.
Optimizing an Empirical Scoring Function for Transmembrane Protein Structure Determination
, 2004
"... We examine the problem of transmembrane protein structure determination. Like many questions that arise in biological research, this problemcannot be addressed generally by traditional laboratory experimentation alone. Instead, an approach that integrates experiment and computation is required. We f ..."
Abstract

Cited by 5 (4 self)
 Add to MetaCart
We examine the problem of transmembrane protein structure determination. Like many questions that arise in biological research, this problemcannot be addressed generally by traditional laboratory experimentation alone. Instead, an approach that integrates experiment and computation is required. We formulate the transmembrane protein structure determination problem as a boundconstrained optimization problem using a special empirical scoring function, called Bundler, as the objective function. In this paper, we describe the optimization problem and its mathematical properties, and we examine results obtained using two different derivativefree optimization algorithms.