The authors tried to establish that A* is much better than traditional branch-and-bound procedures at solving certain types of minimum-penalty job-sequencing problems. Townsend's algorithm (1976) for minimum-penalty job sequencing on one machine with quadratic penalties was implemented both as tree search and as a graph-based A* formation that uses Townsend's lower bounds at nodes as heuristic estimates. The graph implementation took much less time to run, and problem instances of much larger size could be solved. The approach seems to be particularly suitable for sequencing and other optimization problems where lower bounds at nodes can be determined without excessive computational effort.
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