Author: Robert Hyatt
Date: 10:41:57 09/07/01
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On September 07, 2001 at 10:53:33, Peter Fendrich wrote: >> > >Who has the optimal move ordering? I would like to know that person! >I made the same test without hash tables and with a big one and got >similar results which supports your reasoning. Maybe it would be >possible to apply pure knowledge here about "distant king opposition" >(translated from swedish) in closed pawn positions. I will certainly not try but >it might be theoretical possible to get a shorter solution with optimal (for >that program) move ordering. I did this in Cray Blitz _many_ years ago (coordinated squares is the term I hear used most often). And I was amazed that it took longer to find the right move. After a mountain of debugging output, I discovered what I mentioned previously... "hash grafting" (the art of grafting parts of the tree from one zone to another by using the hash table) was helping the dumber version, but not the smarter one. I think the theoretical optimal solution is 26 plies + a capture. This position was in a paper written by Monty Newborn many years ago when he wrote a program that only solved king and pawn endings. We were all amazed when chess 4.6 reported that they solved it in 23 plies in 26 minutes or some such thing, back in 1976 or so. When I tested it on Cray Blitz, we solved it in seconds, which got me to thinking and testing... > >BTW When I looked at your search below I found something strange: >At iteration 11 you have a Hashtab cutoff at ply=8. So remaining depth is say 3. >In order to break here you must have found this position at an earlier iteration >with a reamianing depth > 3. Correct? I can't see how that is possible. >//Peter Correct. Although it is also possible that I screwed myself by leaving an old position.bin (position learning) file lying around. I do that quite often and spend a day debugging nothing. :) And it is simply possible that the 'grafting' problem I mentioned happened there as well. > >
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