Scheduling equal-length jobs with arbitrary sizes on uniform parallel batch machines

Abstract We consider the problem of scheduling jobs with equal lengths and arbitrary sizes on uniform parallel batch machines different capacities. Each machine can only process whose are not larger than its capacity. Several be processed as a simultaneously machine, long their total size does exceed machine’s The objective is to minimize makespan. Under divisibility constraint, we obtain two efficient exact algorithms. For general problem, an 2-approximation algorithm. Previous work has shown that cannot approximated within approximation ratio better 2, unless P = NP, even when all have identical speeds