We have n jobs with release times and due-dates to be scheduled on a single-machine that can handle at most one job at a time. Our objective is to minimize the number of late jobs, ones completed after their due-dates. This problem is known to be solvable in time O(n4). We show that the special case of the problem when job processing times and due-dates are tied so that for each pair of jobs i,...

Local search is an established meta heuristic for scheduling problems. To avoid of getting stucked in a local optimum, the achieved solution is destroyed. Usually, this is done randomly. Here, two problem specific procedures are suggested. One focuses on jobs with the highest difference between the actual processing time and the net processing time of the job and the other one tries to remove j...

Scheduling in Real-time systems differs from scheduling in conventional models in two principal ways: (a) Parameter variability, (b) Existence of complex constraints between jobs. Our work focusses on variable execution times. Whereas traditional models assume fixed values for job execution time, we model execution times of jobs through convex sets. The second feature unique to real-time system...

In many real-time systems, the workload can be characterized as a set of jobs with linear precedence constraints among them. Jobs often have variable execution times and arbitrary release times. We describe here three algorithms that can be used to compute upper bounds on completion times of such jobs scheduled on a priority-driven basis. The algorithmshave different performance and complexity....

In most contemporary systems there are several jobs concurrently competing for shared resources, such as a processor, memory, network, sensors or other devices. Sharing a resource between several jobs requires synchronizing the jobs, specifying when which job will have access to the resource. A common synchronization method is scheduling. Executing a schedule requires switching resource assignm...

In this paper, we study the co-scheduling problems of periodic user transactions and update transactions in real-time database systems for surveillance of critical events. To perform the surveillance functions effectively, it is important to meet the deadlines of all the periodic user transactions and at the same time to maintain the quality of the real-time data objects accessed by them. Unfor...

In this paper, we study the co-scheduling problem of periodic application transactions and update transactions in real-time database systems for surveillance of critical events. To perform the surveillance functions effectively, it is important to meet the deadlines of the application transactions while maintaining the quality of the real-time data objects accessed by them. Unfortunately, these...