Test position: Bishop ending

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muxecoid
Posts: 150
Joined: Sat Jan 30, 2010 9:54 am
Location: Israel

Test position: Bishop ending

Post by muxecoid » Wed Jul 03, 2013 9:45 pm

[D] 2b5/2p5/p1k4p/1p4p1/3K2P1/1P3P2/P1B5/8 b - - 1 41
Happened in one of my games. After thinking for a very long time I played b4. Some strong engines like Kd6 and switch to b4 only if you "show" it to the engine. Do you agree that my b4 was correct? If so it is one of those highly strategic positions where weak human can see something that engine misses.

zullil
Posts: 5432
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Full name: Louis Zulli

Re: Test position: Bishop ending

Post by zullil » Thu Jul 04, 2013 12:28 am

muxecoid wrote:[D] 2b5/2p5/p1k4p/1p4p1/3K2P1/1P3P2/P1B5/8 b - - 1 41
Happened in one of my games. After thinking for a very long time I played b4. Some strong engines like Kd6 and switch to b4 only if you "show" it to the engine. Do you agree that my b4 was correct? If so it is one of those highly strategic positions where weak human can see something that engine misses.
Stockfish says a6a5:

Code: Select all

info depth 44 seldepth 86 score cp 486 nodes 5170694225 nps 7725975 time 669261 multipv 1 pv a6a5 c2d3 c8b7 d4e5 c6c5 d3e4 c5b6 e5f6 c7c5 f6e5 b6c7 e4d3 b7f3 e5f5 c7b6 f5g6 f3g4 g6h6 a5a4 h6g5 a4b3 a2b3 g4d1 d3f5 d1b3 g5f4 c5c4 f5e6 b5b4 f4e3 b6c5 e3e2 c5d4 e6g8 d4c3 g8f7 b3c2

ernest
Posts: 1842
Joined: Wed Mar 08, 2006 7:30 pm

Re: Test position: Bishop ending

Post by ernest » Thu Jul 04, 2013 12:41 am

muxecoid wrote:Some strong engines like Kd6 and switch to b4 only if you "show" it to the engine.
Certainly true with Houdini 3 !

After depth 28:
Analysis by Houdini 3 w32 Nlm:

1. -+ (-1.47): 1...a5 2.Bd3 Kb6 3.Ke5 Bb7 4.Be2 c5 5.a3 Bc6 6.Kf5 Bd5 7.Bd1 c4 8.bxc4 bxc4 9.f4 gxf4 10.Kxf4 Kc5 11.Ke3 Bg8 12.Bf3 Bh7 13.Bd1 c3 14.Bb3 Bb1 15.Be6 Kd6 16.Bc4 Ke5 17.Bf1 Bc2 18.Bg2 Bg6 19.Bf1 Kd5 20.Be2 Bh7 21.Bb5 Kc5 22.Bf1
2. -/+ (-0.75): 1...Kd6 2.b4 Be6 3.a3 Bd5 4.Bd1 Bb7 5.Be2 Bc6 6.Bd1 Bd5 7.Be2 Ba8 8.Bd1 Bd5 9.Be2

maybe the b4 effect only shows at high depth...

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MikeGL
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Re: Test position: Bishop ending

Post by MikeGL » Thu Jul 04, 2013 2:47 am

muxecoid wrote:[D] 2b5/2p5/p1k4p/1p4p1/3K2P1/1P3P2/P1B5/8 b - - 1 41
Happened in one of my games. After thinking for a very long time I played b4. Some strong engines like Kd6 and switch to b4 only if you "show" it to the engine. Do you agree that my b4 was correct? If so it is one of those highly strategic positions where weak human can see something that engine misses.
Critter 1.6 32bit in my slow dual core considers a5 but shifts to b4 after 3min 07s at Depth 21

21/62 03:07 302.412.195 1.623.341 +1.32 b4 Ke5 a5 Bf5 Bb7 Be4+ Kb6 Kd4 c5+ Ke3 Bxe4 fxe4 Kc6 Kd3 Kd6 Ke2 Ke5 Ke3 Kf6 Kd3 Ke6 Kd2 Kd7 Kd3 Kc6 Kc4 Kd6 Kd3 Kc6
21/62 03:07 302.412.195 1.623.341 +1.23 a5 Ke5 Bb7 Bf5 Kc5 Be4 Kb6 a3 c5 Bd5 Bxd5 Kxd5 a4 bxa4 bxa4 Ke4 Ka5 Ke3 Ka6 Kd2 Kb5 Kc3 Kb6 Kd2
21/62 03:07 302.412.195 1.623.341 +0.92 Kd6 b4 Be6 a3 Bd5 Bd1 Ke6 Be2 Ba8 Bd1 Kd6 Be2 Bb7 Bd1 Bd5 Be2 c6 Bd1 Ke6 Be2 Kf6 Bd1


b4 is clearly the best because white threatens a3 then b4, fixing b5 pawn of black to white square. But engine's move, a5, can still win considering black is a pawn up in your position

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