Results 1  10
of
34
Exact algorithms for NPhard problems: A survey
 Combinatorial Optimization  Eureka, You Shrink!, LNCS
"... Abstract. We discuss fast exponential time solutions for NPcomplete problems. We survey known results and approaches, we provide pointers to the literature, and we discuss several open problems in this area. The list of discussed NPcomplete problems includes the travelling salesman problem, schedu ..."
Abstract

Cited by 118 (3 self)
 Add to MetaCart
Abstract. We discuss fast exponential time solutions for NPcomplete problems. We survey known results and approaches, we provide pointers to the literature, and we discuss several open problems in this area. The list of discussed NPcomplete problems includes the travelling salesman problem, scheduling under precedence constraints, satisfiability, knapsack, graph coloring, independent sets in graphs, bandwidth of a graph, and many more. 1
A Computational Study of Constraint Satisfaction for Multiple Capacitated Job Shop Scheduling
 European Journal of Operational Research
, 1996
"... Weintroduce the multiple capacitated job shop scheduling problem as a generalization of the job shop scheduling problem. In this problem machines may process several operations simultaneously.We presentan algorithm based on constraint satisfaction techniques to handle the problem e#ectively. The ..."
Abstract

Cited by 38 (4 self)
 Add to MetaCart
Weintroduce the multiple capacitated job shop scheduling problem as a generalization of the job shop scheduling problem. In this problem machines may process several operations simultaneously.We presentan algorithm based on constraint satisfaction techniques to handle the problem e#ectively. The most importantnovel feature of our algorithm is the consistency checking. An empirical performance analysis is performed using a wellknown set of instances of the job shop scheduling problem and a newly constructed set of instances of the multiple capacitated job shop scheduling problem. We show that our algorithm performs well for both sets of instances.
Nonapproximability results for scheduling problems with minsum criteria
 Proceedings of the 6th International IPCO Conference on Integer Programming and Combinatorial Optimization
, 1998
"... We provide several nonapproximability results for deterministic scheduling problems whose objective is to minimize the total job completion time. Unless P = NP, none of the problems under consideration can be approximated in polynomial time within arbitrarily good precision. Most of our results are ..."
Abstract

Cited by 38 (3 self)
 Add to MetaCart
We provide several nonapproximability results for deterministic scheduling problems whose objective is to minimize the total job completion time. Unless P = NP, none of the problems under consideration can be approximated in polynomial time within arbitrarily good precision. Most of our results are derived by APXhardness proofs.
We show that, whereas scheduling on unrelated machines with unit weights is polynomially solvable, the problem becomes APXhard if release dates or weights are added. We further show APXhardness for scheduling in flow shops, job shops, and open shops. We also investigate the problems of scheduling on parallel machines with precedence constraints and unit processing times, and two variants of the latter problem with unit communication delays; for these problems we provide lower bounds on the worstcase behavior of any
polynomialtime approximation algorithm through the gap reduction technique.
Polynomial time approximation algorithms for machine scheduling: Ten open problems
 Journal of Scheduling
, 1999
"... We discuss what we consider to be the ten most vexing open questions in the area of polynomial time approximation algorithms for NPhard deterministic machine scheduling
problems. We summarize what is known on these problems, we discuss related results, and we provide pointers to the literature.
..."
Abstract

Cited by 36 (2 self)
 Add to MetaCart
We discuss what we consider to be the ten most vexing open questions in the area of polynomial time approximation algorithms for NPhard deterministic machine scheduling
problems. We summarize what is known on these problems, we discuss related results, and we provide pointers to the literature.
Incorporating Efficient Operations Research Algorithms in ConstraintBased Scheduling
 IN PROCEEDINGS OF THE FIRST INTERNATIONAL JOINT WORKSHOP ON ARTIFICIAL INTELLIGENCE AND OPERATIONS RESEARCH
, 1995
"... We address the area of scheduling and the differences between the way operations research and artificial intelligence approach scheduling. We introduce the concept of constraint programming, and describe how operations research techniques can be integrated in constraint programming. Finally, we ..."
Abstract

Cited by 31 (0 self)
 Add to MetaCart
We address the area of scheduling and the differences between the way operations research and artificial intelligence approach scheduling. We introduce the concept of constraint programming, and describe how operations research techniques can be integrated in constraint programming. Finally, we give a short overview of the results obtained with our approach.
Hybrid Genetic Algorithms for Binpacking and Related Problems
 Annals of Operations Research
, 1993
"... The genetic algorithm (GA) paradigm has attracted considerable attention as a promising heuristic approach for solving optimization problems. Much of the development has related to problems of optimizing functions of continuous variables, but recently there have been several applications to problems ..."
Abstract

Cited by 29 (0 self)
 Add to MetaCart
The genetic algorithm (GA) paradigm has attracted considerable attention as a promising heuristic approach for solving optimization problems. Much of the development has related to problems of optimizing functions of continuous variables, but recently there have been several applications to problems of a combinatorial nature. What is often found is that GAs have fairly poor performance for combinatorial problems if implemented in a naive way, and most reported work has involved somewhat ad hoc adjustments to the basic method. In this paper, we will describe a general approach which promises good performance for a fairly extensive class of problems by hybridizing the GA with existing simple heuristics. The procedure will be illustrated mainly in relation to the problem of binpacking , but it could be extended to other problems such as graphpartitioning, parallelmachine scheduling and generalized assignment. The method is further extended by using problem size reduction hybrids. So...
On The Complexity Of Testing Membership In The Core Of MinCost Spanning Tree Games
 INTERNATIONAL JOURNAL OF GAME THEORY
, 1994
"... Let N = f1, ..., ng be a finite set of players and KN the complete graph on the node set N [ f0g. Assume that the edges of KN have nonnegative weights and associate with each coalition S ` N of players as cost c(S) the weight of a minimal spanning tree on the node set S [ f0g. Using reduction to EXA ..."
Abstract

Cited by 27 (8 self)
 Add to MetaCart
Let N = f1, ..., ng be a finite set of players and KN the complete graph on the node set N [ f0g. Assume that the edges of KN have nonnegative weights and associate with each coalition S ` N of players as cost c(S) the weight of a minimal spanning tree on the node set S [ f0g. Using reduction to EXACT COVER BY 3SETS, we exhibit the following problem to be NPcomplete. Given the vector x 2 ! N with x(N ) = c(N ), decide whether there exists a coalition S such that x(S) ? c(S).
The Complexity of Computing Medians of Relations
, 1998
"... Let N be a finite set and R be the set of all binary relations on N . Consider R endowed with a metric d, the symmetric difference distance. For a given mtuple = (R 1 ; : : : ; Rm ) 2 R m , a relation R 2 R that minimizes the function P m k=1 d(R k ; R) is called a median relation of . In the socia ..."
Abstract

Cited by 20 (0 self)
 Add to MetaCart
Let N be a finite set and R be the set of all binary relations on N . Consider R endowed with a metric d, the symmetric difference distance. For a given mtuple = (R 1 ; : : : ; Rm ) 2 R m , a relation R 2 R that minimizes the function P m k=1 d(R k ; R) is called a median relation of . In the social sciences, in qualitative data analysis and in multicriteria decision making, problems occur in which the mtuple represents collected data (preferences, similarities, games) and the objective is that of finding a median relation of with some special feature (representing for example, consensus of preferences, clustering of similar objects, ranking of teams, etc.). In this paper we analyse the computational complexity of all such problems in which the median is required to satisfy one or more of the properties: reexitivity, symmetry, antisymmetry, transitivity and completeness. We prove that whenever transitivity is required (except when symmetry and completeness are also si...