Abstract

INTRODUCTION The "Triangle" benchmark is typically the longest of the Gabriel Lisp benchmarks, taking between 14.44 seconds on the Cray-1 and 1510 seconds on the Xerox Dolphin [Gabriel85]. 1 Triangle performs a classical AI task, in that it solves a puzzle game using a combinatorial search. Unfortunately, the standard implementation of the Triangle benchmark is an embarrassment to the AI and Lisp communities, because it does not utilize the best algorithm, and therefore continues to perpetuate the myth that "Lisp is slow". We show how to speed up Triangle through a combination of memoizing [Bird80] and bit-vector techniques [Baker90], to yield a time of 0.07 seconds on a modern RISC workstation (the 80860-based OKIstation^TM), which is 206 times faster than the Cray-1 speed in [Gabriel85]. Our techniques eliminate redundancy from the computation, which has the effect of eliminating potential parallelism, as well. B. THE STANDARD TRIA

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