Author: J. Wesley Cleveland
Date: 11:51:16 05/14/01
Go up one level in this thread
On May 13, 2001 at 22:42:00, Robert Hyatt wrote: >On May 13, 2001 at 19:48:59, J. Wesley Cleveland wrote: > >>On May 12, 2001 at 20:41:23, Robert Hyatt wrote: >> >>>On May 11, 2001 at 16:50:28, J. Wesley Cleveland wrote: >>> >>>>Okay. With exact results, you only need the number of plies to the next capture >>>>or pawn move stored with each position to solve the 50 move rule problem. >>>>Repititions are a non-problem, i.e. if from position A, you know that position B >>>>is a forced win, *but* the win leads back through A, you would never choose to >>>>move to B, because you would already know there is a shorter win from A. >>> >>> >>>How would you _know_ that either of those positions were forced wins if you >>>don't save _everything_ as you search? >>> >>You know because you have a string of positions in the hash table, each of which >>is one ply closer to mate. There *can't* be a repitition, or it would be a >>different string. It is just like endgame tablebases, which do not need any >>history of positions. > > >I'm not sure I follow. Endgame tables have _all_ positions available during >their creation. That is how the algorithm works.. find a position that is >marked as "unknown" by backtracking from a position marked as "known". Then >you can mark the unknown entry as mate in one more move than the known entry. >But you must have _all_ positions stored during the creation... _every_ one. I thought that is what we were discussing. If you have a hash table large enough to store every position found in the search, then you do not need total path information with each position, which means you could solve chess by considering "only" about 10^25 positions. So, if Moore's law holds up, we could solve chess by the end of the century, rather than by the end of the universe.
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