Author: Robert Hyatt
Date: 15:47:51 05/17/00
Go up one level in this thread
On May 17, 2000 at 18:23:53, Dann Corbit wrote:
>On May 17, 2000 at 10:46:01, Ernst A. Heinz wrote:
>
>>Hi Dann,
>>
>>>What is the best move for this position?
>>>[D] 2kr1b1r/ppp1qppp/2p2n2/7b/4P3/2NBBP2/PPP1Q1PP/R3K2R b KQ -
>>
>>"DarkThought WMCC'99" sticks with Qe5 from the very beginning and
>>scores it as slightly negative for Black after iteration #14.
>>
>>14.01 Qe5 O-O-O Bb4 Nb1 Bc5 Nd2 Nd7 Nc4 Qe6 g4 =-0.31 #605379154
>>
>>>How long does your program take to find Bxa7?
>>>[D] 2kr1b1r/pppq1ppp/3p4/3Pp3/1n2P1n1/2N1BN2/PPP2PPP/R2Q1RK1 w - - acd 14; acn
>>>122077893; acs 600; ce 32; pv Bxa7;
>>
>>"DarkThought WMCC'99" locks onto Bxa7 from the start and scores
>>it as +1.21 for White after iteration #14.
>>
>>14.01 Bxa7 b6 a4 Kb7 =1.21 #127027547
>
>You must have a pretty amazing evaluation to find it from the start. When I
>looked at the move Bxa7, I thought it quite repellant. I would trap the bishop
>like this:
>[D] 2kr1b1r/B1pq1ppp/1p1p4/3Pp3/1n2P1n1/2N2N2/PPP2PPP/R2Q1RK1 w - -
>With an eye to Bishop stew down the road sometime.
>--
>C.A.P. FAQ: ftp://38.168.214.175/pub/Chess%20Analysis%20Project%20FAQ.htm
I think playing Bxa7 very quickly is a bug. Because you are right, trapping
the bishop is easy, and breaking the trap is deep. For every game you win by
playing Bxa7 you will lose 10.
I think the right way to do this is to penalize the bishop getting trapped, and
then make the search prove that it can grab the pawn _and_ get the bishop out of
the b6 trap, before accepting the score as good...
I ran this on the quad xeon, just to make sure. Crafty finds that Bxa7 is
playable after just over 4 minutes. It won't touch it until it is sure it
can extricate the bishop...:
(3) 13-> 1:09 0.29 1. a3 Na6 2. Ng5 Nf6 3. Qe2 h6 4. Nf3
Kb8 5. h3 Qe7 6. Qc4 Nc5 7. Bxc5 dxc5
(2) 14 1:22 0.31 1. a3 Na6 2. Ng5 Nf6 3. Qe2 h6 4. Nf3
Kb8 5. Nb5 b6 6. Nc3 Qc8 7. Qc4 Be7
14 4:37 ++ 1. Bxa7!!
14 7:04 1.02 1. Bxa7 b6 2. a4 Kb7 3. a5 Ra8 4. axb6
cxb6 5. Qe2 Rxa7 6. Rxa7+ Kxa7 7. h3
Be7 8. hxg4 Qxg4 9. Ra1+ Kb8
15 8:26 1.21 1. Bxa7 b6 2. a4 Kb7 3. a5 Ra8 4. axb6
cxb6 5. Qe2 Rxa7 6. Rxa7+ Kxa7 7. Ra1+
Kb8 8. Ra4 Nxd5 9. exd5 Qf5 10. Qc4
There are still several programs around that swallow a pawn on a7/h7 and then
get choked on it later... I prefer the "human approach" here myself. Don't
do it unless I am sure it works, rather than do it unless I can see it doesn't
work...
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