The Robotics Institute

Carnegie Mellon Robotics Institute

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Abstract

Oversubscribed scheduling problems have been approached using both direct representations of the solution space and indirect, permutation-based representations(coupled with a schedule builder to produce the corresponding schedule). In some problem contexts, permutation-based search methods have been shown to outperform schedule-space search methods, while in others the opposite has been shown to be the case. We consider two techniques for which this behavior has been observed: TaskSwap (TS), a schedule-space repair search procedure, and Squeaky Wheel Optimization (SWO), a permutation-space scheduling procedure. We analyze the circumstances under which one can be expected to dominate the other. Starting from a real-world scheduling problem where SWO has been shown to outperform TS, we construct a series of problem instances that increasingly incorporate characteristics of a second real-world scheduling problem, where TS has been found to outperform SWO. Experimental results provide insights into when schedule-space methods and permutation-based methods may be most appropriate. Finally, we consider opportunities for improving performance by integrating the two approaches into a hybrid approach that exploits both search spaces.

Notes

Associated Center(s) / Consortia: Center for Integrated Manfacturing Decision Systems

Associated Lab(s) / Group(s): Intelligent Coordination and Logistics Laboratory

Associated Project(s): AMC Barrelmaster Scheduling

Text Reference

Laurence Kramer, Laura Barbulescu, and Stephen Smith , "Searching Alternate Spaces to Solve Oversubscribed Scheduling Problems," tech. report CMU-RI-TR-08-12, Robotics Institute, Carnegie Mellon University, March, 2008

BibTeX Reference

@techreport{Kramer_2008_6017,
   author = "Laurence Kramer and Laura Barbulescu and Stephen {Smith }",
   title = "Searching Alternate Spaces to Solve Oversubscribed Scheduling Problems",
   booktitle = "",
   institution = "Robotics Institute",
   month = "March",
   year = "2008",
   number= "CMU-RI-TR-08-12",
   address= "Pittsburgh, PA",
}

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