M. Wodecki

Robustness of the Uncertain Single Machine Total Weighted Tardiness Problem with Elimination Criteria Applied

In the paper we investigate an uncertain single machine total weighted tardiness problem where uncertainty of times of jobs execution and jobs deadlines are modeled by random variables with a normal distribution. We check the influence of applying elimination criteria to the robustness of the determined solutions. Results are very promising and encourage further research.

Two level algorithm with Tabu Search optimization for task scheduling problem in computing cluster environment

This article presents a proposal of solution for the problem of optimal task allocation and scheduling for computing cluster with multiple nodes. The above issue is considered as Two-Dimensional Packing Problem. We present the two level algorithm where Tabu Search is used to minimize relatively low accuracy of greedy packing strategy. The paper contains the results of computational experiments on the scalability and performance of the presented method, compared to classic greedy strategies.

Big valley in scheduling problems landscape — Metaheuristics with reduced searching area

Created in the 90s of the past century methods of constructing algorithms (metaheuristic), inspired by the no free lunch theorem of Wolpert and Macready, using specific properties of problems, do not meet present expectations of practitioners. Commonly used artificial intelligence algorithms in recent years have also proved to be ineffective in solving a large group of extremely difficult instances of various problems. In the work we present some empirical methods of exploration of solution space in optimization problems whose solutions are represented by permutations. While sampling the set of permissible solutions we designate the histogram of the frequency of occurrence of local minima and on this basis we verify the statistical hypothesis concerning the (normal) distribution of occurrence of these minima. Due to this process we can flexibly change the “radius” of the searched area. Computational experiments performed on examples of the job shop problem are promising and inspire to conduct further research in this direction.