Author: Peter McKenzie
Date: 12:45:55 04/18/02
Go up one level in this thread
On April 18, 2002 at 05:27:18, Ed Schröder wrote: >On April 17, 2002 at 17:45:03, Peter McKenzie wrote: > >>On April 17, 2002 at 16:53:30, Gian-Carlo Pascutto wrote: >> >>>On April 17, 2002 at 16:40:01, Dann Corbit wrote: >>> >>>>I don't see how it can completely remove the tactic from ever being seen unless >>>>the implementation of null move is broken. >>> >>>If it has a zugzwang, you will _never_ see it if you don't check for it >>>(verification search, double nullmove), or use another trick like force >>>nullmoves away from the root (that is what Crafty does). >>> >>>You can always play the 'nullmove' no matter what depth, so you'll >>>never realize the nullmove is no good. >>> >>>i.e. you make an illegal move that is not possible in the real game, and >>>increasing search depth won't change this. >> >>Yes, you are correct. Some programs can never solve the following: >> >>[D]8/8/2p5/pkp3R1/7B/P7/2p3K1/8 w - - > >Rebel uses null-move since its latest version, no problem, just 8 seconds to see >the draw. Maybe it is a matter of eval too, could be... Also depends on when you do nullmove. After a4+ Kb6 Bf2 c1Q Rxc5 Qxc5 Kh1, white has Q vs B, it seems Rebel doesn't do nullmove in that position but some programs do. > >Ed > >=================== > >00:00:02.8 0,01 12 853807 Rxc5+ Kxc5 Bg5 Kd4 Kf3 Kd3 Bf4 c5 >00:00:03.3 0,00 13 1771119 Rxc5+ Kxc5 Bg5 Kd4 Kf3 Kd3 Bf4 c5 >00:00:05.6 -1,41 14 4456961 Rxc5+ Kxc5 Bg5 Kc4 Kf2 Kb3 Bc1 Ka2 >00:00:08.7 0,00 14 7068951 a4+ Kb6 Bf2 c1Q Rxc5 Qxc5 Kh1 >00:00:11.1 0,00 15 11124240 a4+ Kb6 Bf2 c1Q Rxc5 Qxc5 Kh1 >00:00:18.6 0,00 16 20139015 a4+ Kb6 Bf2 c1Q Rxc5 Qxc5 Kh1 >00:00:30.6 0,00 17 34891048 a4+ Kb6 Bf2 c1Q Rxc5 Qxc5 Kh1 >00:00:53.2 0,00 18 64932256 a4+ Kb6 Bf2 c1Q Rxc5 Qxc5 Kh1 > >Revel XP (alpha), A1400, 60 Mb > > >>http://homepages.caverock.net.nz/~peter/eg_test/pet013.htm >> >>> >>>-- >>>GCP
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