Author: Tim Foden
Date: 11:21:49 07/05/03
Go up one level in this thread
On July 05, 2003 at 02:15:11, Ryan B. wrote:
>[d]2r2rk1/p4ppp/1p2nq2/2nRp3/1Q2P3/P1P1BP1P/4B2P/3R2K1 w - - 0 1
>
>Most programs see this as at least a 1-pawn advantage for black. My program
>does not see the advantage reporting an almost even score (-0.21). Because I am
>not a strong chess player I cannot tell if my program is missing something in
>its eval or missing a good move to pruning. My guess for now is that it has
>something to do with king safety but I could be way off. Any help would be
>greatly appreciated, thanks.
>
>-Ryan
GLC 3.00 static eval of this position gives: white score = -0.254 pawns.
After a 12 ply search, GLC gives this line:
12 1:53.35 -0.897 87038k c4 Rfe8 2. Rd6 Qh4 3. Qb2 f6 4. Kg2 Rc7 5. Qc2 Ng5
6. Bxg5 Qxg5+ 7. Kh1
So that static eval score at the end gives: white score = -0.897
This is a change of around 0.75 pawns. Unfortunately there is not any single
evaluation term that changes, but rather there are many smaller changes.
Rough summary of relative changes:
Pawn structure -0.11
Pawn positional -0.13
Knight positional +0.04
Bishop positional -0.17
Bishop pair -0.26
Rook positional -0.14
Queen positional +0.08
King positional -0.12
King saftey +0.03
King attack -0.08
I realise this doesn't add up quite to 0.75, its more like 0.89, but I'm afraid
I've looked at GLC's output for some time now, but I still can't find where my
maths is wrong! It'll be close enough to give you an idea.
In fact, you can run GLC, enter a FEN (FEN <fen-str>) and ask it to give a score
(SC), and it will give lots of details. This is what I used to give the summary
above. The output looks like this (first 15 lines only)(GLC works in 1000ths of
a pawn):
Game stage: Middle game
w pawn (h2) doubled -30
w pawn (h2) isolated -104
w pawn (a3) isolated -104
w pawn (c3) isolated -104
w pawn (f3) singly connected 20
w pawn (f3) weak -97
w pawn (h3) doubled -30
w pawn (h3) isolated -104
w pawn (e4) singly connected 20
b pawn (e5) singly connected 20
b pawn (e5) weak -97
b pawn (b6) singly connected 20
b pawn (a7) singly connected 20
Cheers, Tim.
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