Author: Robert Hyatt
Date: 21:49:13 06/09/00
Go up one level in this thread
On June 09, 2000 at 13:59:44, blass uri wrote:
>On June 09, 2000 at 12:11:16, Ernst A. Heinz wrote:
>
>>>[D]8/8/Pk5K/2p5/2P1pp2/8/5P1P/8 w - - 0 1
>>>
>>>Programs cannot see at evaluation time that black is winning because of
>>>unstoppable pawn.
>>>
>>>If I give them to analyze at 1 ply depth they give a big advantage for white.
>>
>>What do you mean by "big advantage"?
>>
>>"DarkThought WCCC'99" knows about White's unstoppable passed Pawn
>>on h2 and it also knows about the potential breakthrough of the
>>two Black Pawns on e4 and f4. Both somehow cancel each other out
>>in the static evaluation such that the overall score is just the
>>+1 material advantage of White.
>>
>>=Ernst=
>
>Some other programs gave more than +2 for white and in one of the cases(I think
>it was hiarcs7.32) they gave even about +7 pawns at 1 ply depth.
>
>Uri
WIth a 4 ply search, I see black winning. The problem is that white gets to do
one horizon move, pushing his pawn to the 7th rank where black is obligated to
rip it. Then black makes a passer that queens first and ends the game. I don't
know that I want to solve this totally in eval, because it is hard to handle the
'horizon' cases there. But a 4 ply search takes essentially no time, and is
very accurate:
nss depth time score variation (1)
1 0.00 -0.20 1. a7 Kxa7
1 0.00 0.02 1. h4 Kxa6
1 0.00 ++ 1. Kg6!!
1 0.00 2.25 1. Kg6
1-> 0.00 2.25 1. Kg6
2 0.00 2.15 1. Kg6 Kc6
2 0.00 ++ 1. a7!!
2 0.00 2.96 1. a7 Kb7 2. Kg6
2 0.00 ++ 1. Kg5!!
2-> 0.01 3.35 1. Kg5
3 0.01 -- 1. Kg5
3 0.01 2.67 1. Kg5 e3 2. a7 exf2 3. a8=N+ Kc6
3 0.01 ++ 1. a7!!
3 0.01 5.80 1. a7 Kxa7 2. Kg6 Kb6
3-> 0.01 5.80 1. a7 Kxa7 2. Kg6 Kb6
4 0.01 -- 1. a7
4 0.02 -6.27 1. a7 Kxa7 2. h4 e3 3. fxe3 fxe3
4 0.02 ++ 1. Kg5!!
4 0.02 -3.81 1. Kg5 e3 2. fxe3 fxe3 3. Kf6
4-> 0.03 -3.81 1. Kg5 e3 2. fxe3 fxe3 3. Kf6
If nothing else, it does realize that this is won in the eval, after the horizon
move is cleared out...
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