No-wait Job Shop Scheduling Research Articles

No-wait Job Shop Scheduling: Tabu Search and Complexity of Subproblems

This paper deals with the no-wait job shop problem with a makespan objective. We present some new theoretical properties on the complexity of subproblems associated with a well-known decomposition approach. Justified by the complexity results, we implement a fast tabu search algorithm for the problem at hand. It is extensively tested on known benchmark instances and compares favorably to the best existing algorithms for the no-wait job shop as well as the no-wait flow shop.

Minimizing Makespan in No-Wait Job Shops

In this paper, we study polynomial time approximation schemes (PTASes) for the no-wait job shop scheduling problem with the makespan objective function. It is known that the problem is MaxSNP-hard in the case when each job is allowed to have three operations or more. We show that if each job has at most two operations, the problem admits a PTAS if the number of machines is a constant (i.e., not part of the input). If the number of machines is not a constant, we show that the problem is hard to approximate within a factor better than 5/4.

Inapproximability results for no-wait job shop scheduling

We investigate the approximability of the no-wait job shop scheduling problem under the makespan criterion. We show that this problem is APX -hard (i) for the case of two machines with at most five operations per job, and (ii) for the case of three machines with at most three operations per job. Hence, these problems do not possess a polynomial time approximation scheme, unless P= NP .

Approximative procedures for no-wait job shop scheduling

In this article we consider the no-wait job shop problem with makespan objective. Based on a decomposition of the problem into a sequencing and a timetabling problem, we propose two local search algorithms. Extensive computational tests in which the algorithms compare favorably to the best existing strategies are reported. Although not specifically designed for that purpose, our algorithms also outperform one of the best no-wait flow shop algorithms in literature.

A polynomial algorithm for a two-machine no-wait job-shop scheduling problem

This paper considers the no-wait scheduling of n jobs, where each job is a chain of unit processing time operations to be processed alternately on two machines. The objective is to minimize the mean flow time. We propose an O(n6)-time algorithm to produce an optimal schedule. It is also shown that if zero processing time operations are allowed, then the problem is NP-hard in the strong sense.

A pseudo-polynomial algorithm for a two-machine no-wait job-shop scheduling problem

An O( n 5 N) algorithm is proposed for the n-job problem 2/ n/ J, no-wait, pt ji =1/ C max, where N is the total number of tasks of all jobs.