Author: Bruce Moreland
Date: 10:44:32 07/11/98
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On July 11, 1998 at 11:45:25, blass uri wrote: >I am interested in positions only one program can solve > >Vincent Diepeveen posted on June 29 the following 2 positions >r4rk1/pp1n1p1p/1nqP2p1/2b1P1B1/4NQ2/1B3P2/PP2K2P/2R5 w - - bm > >the solution is Rxc5 and diep found the move after 6:42 >and found the advamtage for white after 13:14 >he used 60MB hash tables >and I think he used pentium200MMX >my programs found only Bf6 with draw. I thought I posted something about this last week. Mine finds this in two minutes on a P2/300. The score it gets isn't great, it's a little negative. Other versions have found this quickly with scores of +2 or more. >can another program solve this position in 1 hour? > >the second position: >r1b2rk1/1p1nbppp/pq1p4/3B4/P2NP3/2N1p3/1PP3PP/R2Q1R1K w - - bm Rxf7 >diep found the move after 22 minutes and 43 seconds This one takes four minutes to get a slight positive score, five minutes is +1. I like the Nolot positions, I've been fiddling with them for a few years. If you want to see more from me, look for "Nolot" in the "old" archives in r.g.c.c, or perhaps even just rec.games.chess. I can get solutions in some of the other Nolot positions as well. >can another program find this move in 1 hour? > >(according to Robert hyatt deep thought solved the position after 2 minutes but >I cannot buy deep thought so it is not important for me) > >in Rebel's homepage there is mate in 30 Rebel can find(all the moves of the >loser are forced). > >can another chess program find the mate? I can't find it, feel free to post it. Long mates are often the result of positions where one side is in check and has only one legal way out. One very old extension in computer chess involves extending when you make a move that gives check. If you also extend on the reply, when there is only one way out, you get the checking move and the reply without decreasing depth at all. If there is a long forcing sequence you can find mates in very large numbers of moves in just a few nodes. This has been well-known for years. It is hard to find long mates that don't involve this extension. bruce
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