A polynomial algorithm is proposed for two scheduling problems for which the complexity status was open. A set of jobs with unit processing times, release dates and outtree precedence relations has to be processed on parallel identical machines such that the total completion time ∑ C j is...

Problems with unit execution time tasks and two identical parallel processors have received a great deal of attention in scheduling theory. In contrast to the conventional models, where each task requires only one processor, we consider a situation when a task may require both processors...

In this paper we study the single-machine problem 1|chains(l), p j =p|∑ C j in which jobs with constant processing times and generalized precedence constraints in form of chains with constant delays are given. One has to schedule the jobs on a single machine such that all delays between...