Author: Gordon Rattray
Date: 05:36:30 12/22/01
Go up one level in this thread
On December 22, 2001 at 07:56:00, Steffen Jakob wrote: >On December 22, 2001 at 07:47:24, José Carlos wrote: > >>On December 22, 2001 at 07:12:00, Steffen Jakob wrote: >> >>>Hi! >>> >>>I ran the JenoBan endgame test suite which I got from Lyapko Georges web server >>>(http://www.geocities.com/lyapko/jenoban.htm). This is position #79 (the id tag >>>is missing in the epd file from this server): >>> >>>r2k1B2/7R/p7/8/8/8/8/4K3 w - - bm Bc5; (JenoBan_TofE) #79 white_wins >>> >>>[D]r2k1B2/7R/p7/8/8/8/8/4K3 w - - >>> >>>Hossa switches between Bb4 and Bc5 but both with a drawish score. Crafty prefers >>>Bd6 on my machine, also with a drawish score. Can someone please explain why Bc5 >>>is the best move here and how it wins? Or is this position broken? >>> >>>Greetings, >>>Steffen. >> >> After analyzing for a while with Averno, I believe the position is drawn. > >Hmm, I think this is the winning idea: > >1. Bc5 Rc8 2. Bb6+ Ke8 3. Bc7 >Now black can only move his pawn >3... a5 4. Kd1 a4 5. Kc1 a3 6. Kb1 a2+ 7. Ka1! +- > >and > >1. Bc5 Kc8 2. Ba7 with the same pattern as above: +- Analysis from Deep Junior 7 agrees: ... 1.Bb4 Kc8 2.Ba5 Rb8 3.Rc7+ Kd8 4.Rg7+ Kc8 5.Kf2 Rb5 6.Bc3 Rb7 7.Rg8+ Kd7 8.Be5 a5 9.Ke3 ± (0.99) Depth: 17 00:01:39 91373kN, tb=83344 1.Bc5! +- (1.46) Depth: 17 00:01:40 91373kN, tb=83647 1.Bc5! +- (1.76) Depth: 18 00:02:04 123700kN, tb=138620 1.Bc5 Rc8 2.Bb6+ Ke8 3.Bc7 a5 4.Kd2 a4 5.Kc3 a3 6.Kb3 a2 7.Kb2 a1Q+ 8.Kxa1 Ra8+ 9.Kb2 Rc8 +- (1.76) Depth: 19 00:02:41 180865kN, tb=256115 1.Bc5 Rc8 2.Bb6+ Ke8 3.Bc7 a5 4.Kd2 a4 5.Kc3 a3 6.Kb3 a2 +- (1.76) Depth: 20 00:03:54 308310kN, tb=497019 1.Bc5! +- (2.06) Depth: 21 00:04:41 393042kN, tb=649715 1.Bc5! +- (2.36) Depth: 22 00:08:32 814375kN, tb=1294091 1.Bc5! +- (2.66) Depth: 23 00:16:34 1533802kN, tb=2741006 1.Bc5! Rb8 2.Rh8+ Kc7 3.Bd6+ Kxd6 +- (#19) Depth: 23 00:20:13 1766967kN, tb=3303831 (Rattray, 22.12.2001) Both Fritz7 and Shredder5 also see mate (mate in 23, with Rc8 being played as Black's first move) Gordon > >Greetings, >Steffen. > >> >> José C.
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