Heuristics: intelligent search strategies for computer problem solving
Heuristics: intelligent search strategies for computer problem solving
Depth-first iterative-deepening: an optimal admissible tree search
Artificial Intelligence
Search in Artificial Intelligence
Search in Artificial Intelligence
An architecture of a dataflow single chip processor
ISCA '89 Proceedings of the 16th annual international symposium on Computer architecture
Thread-based programming for the EM-4 hybrid dataflow machine
ISCA '92 Proceedings of the 19th annual international symposium on Computer architecture
EMC-Y: parallel processing element optimizing communication and computation
ICS '93 Proceedings of the 7th international conference on Supercomputing
An Improved Bidirectional Heuristic Search Algorithm
Journal of the ACM (JACM)
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Numeric scientific problems have been the main focus of supercomputing as their numerous implementations on various multiprocessors indicate. Nonnumeric problems on the other hand have received very little attention for parallel implementation due to their irregular behaviors and a large amount of resource usage. This report presents our experiences implementing difficult nonnumeric problems on the EM-4 multiprocessor, believing that supercomputers should also be able to effectively execute nonnumeric problems if they are to be considered 'supercomputers.' We selected two typical search problems, the Eight-Puzzle and the Tower-of-Hanoi. Two parallel search techniques are used to implement the search problems, unidirectional and bidirectional heuristic search. A total of eight different programs has been implemented on the EM-4 multiprocessor with realistic problem sizes. Execution results demonstrate that the parallel bidirectional heuristic search can solve the tree depth 20 to 40 of the Eight-Puzzle in an optimal or near optimal number of iterations in less than two seconds, and is highly scalable as it gives over 40-fold speedup for both problems on 80 processors.