Author: Bruce Moreland
Date: 09:06:55 07/19/99
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On July 18, 1999 at 03:01:33, Dave Gomboc wrote: >In the past, people have discussed how difficult it can be to debug a chess >program due to non-deterministic behavior. Clearly, this can arise from a >multi-threaded search. If, however, the search is single-threaded (and >discounting the play from the start of the game until the end of the opening >book), what factors, if any, might allow a program to still not play identically >each time? Retention of data across searches, and timing inaccuracies. If you try to play over a game again, it's unlikely that you'll have the same amount of time in both cases. And if you don't clear your hash table between searches, who knows what you'll find in there and how that will affect your search. The kind of thing I think you are really referring to is instabilities caused by hash table, pruning based upon search bounds, etc. This causes strange behavior, but it should be the same strange behavior each time you do a search. If you have a single-threaded program and tell it to search 10 plies, then stop it and tell it to search the same 10 plies again, it should search the same tree and produce the same result. bruce
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