Author: Dieter Buerssner
Date: 08:35:31 10/22/05
Go up one level in this thread
On October 22, 2005 at 11:05:21, Günther Simon wrote: >On October 22, 2005 at 09:34:42, Uri Blass wrote: > >>On October 22, 2005 at 08:08:47, Günther Simon wrote: >> >>>This position really happened in one of my RWBC games today >>>and it revealed a bug in a program. 6 men say it is a win. >>>(Shredder Oracle : M27 with best play) >>>I am not sure though, if there are programs, which are able >>>to win this without tablebases at all? (in reasonable time ;) >>> >>>Guenther >>> >>>[D]4r3/8/8/8/8/6bk/7p/3R3K b - - 0 76 >> >>I doubt if there are programs that can find it without tablebases at reasonable >>time because I expect KRB vs KR to be prune based on no threat but >>Yace with 5 piece tablebases agree with shredder Oracle >> >>New game, 4320'/1 >>4r3/8/8/8/8/6bk/7p/3R3K b - - 0 1 >> >>Analysis by Yace 0.99.87: >> >... > >>1...Bf4 2.Rf1 Kg4 3.Rb1 Rc8 4.Rf1 Be3 5.Kxh2 Rd8 6.Kg2 Rd2+ 7.Kh1 Bf2 8.Kg2 Bg3+ >>9.Kg1 Re2 10.Rd1 Bf4 11.Rd3 Be3+ 12.Kf1 Kf3 13.Rd7 Rh2 14.Rf7+ Bf4 15.Rg7 Rc2 >>16.Re7 Rb2 17.Re8 >> -+ (-#27) Depth: 22/51 00:29:39 2527052kN >> >>(, 22.10.2005) >> >>Uri > >Thanks for the cpu time Uri. I have one question though, did you >analyse this with 5 men + Yaces' bitbases or without bitbases? >(Those would probably speed it up a 'bit') Günther, I didn't try but I doubt that bitbases can help much here. Yace does not use KRBKR bitbase. 4-men bitbases cannot help at all, to see a huge score here - they can only help to prune some branches faster. Also note that the engine was not slowed down very much by TB-accesses. Yace found a significant score rather fast: [from Uri's post] 1...Bf4 2.Rf1 -+ (-13.23) Depth: 22/44 00:00:49 41473kN [over 800 knodes/s] Only showing a mate score needed very long. I guess, this is not easy to avoid, neither is it important for a game. Bitbases will typically not help, to show a mate score. Even when Yace had KRBKR bitbase, a winning position might be scored +15 (could show +100 or mate in 500 or something, but that is another thing). This would not be enough to show the real mate. It could help to find a really significant score faster. Regards, Dieter
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