A hybrid genetic algorithm (HGA) is proposed for the single machine, single
stage, scheduling problem in a sequence dependent setup time environment w
ithin a fixed planning horizon (SSSDP). It incorporates the elitist ranking
method, genetic operators, and a hill-climbing technique in each searching
area. To improve the performance and efficiency, hill climbing is performe
d by uniting the Wagner-Whitin Algorithm with the problem-specific knowledg
e. The objective of the HGA is to minimize the sum of setup cost, inventory
cost, and backlog cost. The HGA is able to obtain a superior solution, if
it is not optimal, in a reasonable time. The computational results of this
algorithm on real life SSSDP problems are promising. In our test cases, the
HGA performed up to 50% better than the Just-In-Time heuristics and 30% be
tter than the complete batching heuristics.