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Position crafty and stockfish both badly mis-evaluate

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Miguel A. Ballicora

Joined: 09 Mar 2006
Posts: 2732
Location: Chicago, Illinois, USA

Post subject: Re: Position crafty and stockfish both badly mis-evaluate Posted: Fri Jul 30, 2010 6:06 am

BubbaTough wrote:

This position is tricky because the b pawn in some positions can be forced to advance letting white convert his 2nd a pawn into a b pawn, which will foil most evals if done near the leafs of the tree. If you made the b pawn into a pawn on any other file, I expect more programs would understand this position better.

When trying to fix things in these positions, care must be taken. This particular positions is drawn, but there are similar positions which are not.

-Sam

Gaviota was supposed to know all this but this position is very tricky for other reasons.
First of all, white can force black to take the bishop, and if the program does not recognize KPPKP with two rook pawns as draw, it will keep giving a high positive score.
Second, if there is no detection of stalemate in quies, the search can wisely direct the PV to make sure that always the last quies move is taking the b pawn with stalemate. The evaluation will be with a winning score (since the pawn now is in the "b" column).
Third, if the futility margin is not big enough in quies(), it will make the whole thing worst, particularly with an evil interaction with the hashtables. I needed to correct all this three things, and now it works:

Gaviota 0.76.6-modified.
No tablebases

Code:

setboard 2k5/8/Pp1K4/8/7B/8/P7/8 w - - 0 1 bm a4; id "Fine 149 draw";
d
+-----------------+
| . . k . . . . . |
| . . . . . . . . |
| P p . K . . . . |
| . . . . . . . . | Castling:
| . . . . . . . B | ep: -
| . . . . . . . . |
| P . . . . . . . |
| . . . . . . . . | [White]
+-----------------+

tbuse off
analyze
********* Starts iterative deepening, thread = 0
set timer to infinite
25 1: 0.0 +1.46 1.Kc6
124 2 0.0 :-(
215 2: 0.0 +0.19 1.Kc6 Kb8
598 3: 0.0 +0.18 1.Kc6 Kb8 2.Bg3+ Ka7
2096 4: 0.0 +0.19 1.Kc6 Kb8 2.Kb5 Ka7
6849 5: 0.0 +0.19 1.Kc6 Kb8 2.Bg3+ Ka8 3.Kb5 Ka7
9286 6 0.0 +0.19 1.Kc6 Kb8 2.Kb5 Ka8 3.Bf2 Ka7
22413 6: 0.1 +0.19 1.Kc6 Kb8 2.Kb5 Ka8 3.Bf2 Ka7
28938 7 0.1 +0.19 1.Kc6 Kb8 2.Bg3+ Ka7 3.Kb5 Ka8 4.a4 Ka7
50131 7 0.2 +0.19 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc8 Ka8 4.Bb8 b5
62389 7: 0.2 +0.19 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc8 Ka8 4.Bb8 b5
80678 8 0.3 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc8 Ka8 4.Bb8 b5
5.a7 b4
145606 8: 0.4 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc8 Ka8 4.Bb8 b5
5.a7 b4
175886 9 0.5 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc8 Ka8 4.a4 Ka7
5.Bb8+ Ka8 6.a7 b5
305102 9: 0.7 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc8 Ka8 4.a4 Ka7
5.Bb8+ Ka8 6.a7 b5
381384 10 0.8 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc6 Ka8 4.Bf2
Ka7 5.a4 Kb8 6.a7+ Ka8
638300 10: 1.2 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc6 Ka8 4.Bf2
Ka7 5.a4 Kb8 6.a7+ Ka8
748613 11 1.4 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc6 Ka8 4.Bf2
Ka7 5.Kb5 Ka8 6.a4 Kb8
1194167 11: 2.0 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc6 Ka8 4.Bf2
Ka7 5.Kb5 Ka8 6.a4 Kb8
1505765 12 2.6 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc6 Ka8 4.Kc7
Ka7 5.Kc8 Ka8 6.Bb8 b5 7.a7 b4
2259774 12: 3.6 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc6 Ka8 4.Kc7
Ka7 5.Kc8 Ka8 6.Bb8 b5 7.a7 b4
2894063 13 5.0 +0.20 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc6 Ka8 4.Kc7
Ka7 5.Kc8 Ka8 6.a4 Ka7 7.Bb8+ Ka8 8.a7
b5
3035733 13 5.1 +0.20 1.Kc6 Kb8 2.a4 Ka7 3.Kb5 Ka8 4.Bf2 Kb8
5.a7+ Kb7 6.Bd4 Ka8 7.Ka6 b5
4195838 13: 6.8 +0.20 1.Kc6 Kb8 2.a4 Ka7 3.Kb5 Ka8 4.Bf2 Kb8
5.a7+ Kb7 6.Bd4 Ka8 7.Ka6 b5
5935338 14 9.9 +0.20 1.Kc6 Kb8 2.Bg3+ Ka7 3.Kb5 Ka8 4.a4 Ka7
5.Bf4 Ka8 6.Be3 Kb8 7.Kc6 Ka8 8.a7 b5
8741050 14: 14.3 +0.20 1.Kc6 Kb8 2.Bg3+ Ka7 3.Kb5 Ka8 4.a4 Ka7
5.Bf4 Ka8 6.Be3 Kb8 7.Kc6 Ka8 8.a7 b5

with tablebases

Code:

analyze
********* Starts iterative deepening, thread = 0
set timer to infinite
25 1: 0.0 +1.46 1.Kc6
120 2 0.0 :-(
211 2: 0.0 +0.19 1.Kc6 Kb8
559 3: 0.0 +0.18 1.Kc6 Kb8 2.Bg3+ Ka7
1363 4: 0.0 +0.19 1.Kc6 Kb8 2.Kb5 Ka7
4083 5: 0.0 +0.19 1.Kc6 Kb8 2.Bg3+ Ka8 3.Kb5 Ka7
5038 6 0.0 +0.19 1.Kc6 Kb8 2.Kb5 Ka8 3.Bf2 Ka7
9017 6: 0.0 +0.19 1.Kc6 Kb8 2.Kb5 Ka8 3.Bf2 Ka7
11984 7 0.1 +0.19 1.Kc6 Kb8 2.Bg3+ Ka7 3.Kb5 Ka8 4.Bc7
Ka7
14472 7 0.1 +0.19 1.Bg3 Kb8 2.Kd7+ Ka7 3.Kc8 Ka8 4.Bb8 b5
19252 7 0.1 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.a7 Kb7 4.Bd4 Ka8
22091 7: 0.1 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.a7 Kb7 4.Bd4 Ka8
25991 8 0.2 +0.19 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka7
29635 8 0.2 +0.19 1.Kc6 Kb8 2.Bf2 Ka8 3.Kb5 Kb8 4.Bd4 Ka7
41888 8: 0.2 +0.19 1.Kc6 Kb8 2.Bf2 Ka8 3.Kb5 Kb8 4.Bd4 Ka7
49934 9 0.2 +0.20 1.Kc6 Kb8 2.Bg3+ Ka7 3.Kb5 Ka8 4.Bc7
Ka7 5.a4 Ka8
57226 9 0.3 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.a7+ Ka8
5.Bd4 b5
80054 9: 0.3 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.a7+ Ka8
5.Bd4 b5
96398 10 0.4 +0.20 1.a4 Kb8 2.Kc6 Ka7 3.Kb5 Ka8 4.Bg3 Ka7
5.Bc7 Ka8
159552 10: 0.5 +0.20 1.a4 Kb8 2.Kc6 Ka7 3.Kb5 Ka8 4.Bg3 Ka7
5.Bc7 Ka8
181370 11 0.5 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.a7+ Ka8
5.Kb5 Kb7 6.Bd4 Ka8
259037 11: 0.7 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.a7+ Ka8
5.Kb5 Kb7 6.Bd4 Ka8
331581 12 0.9 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka8
5.Bg1 Kb8 6.Be3 Ka8
621119 12: 1.5 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka8
5.Bg1 Kb8 6.Be3 Ka8
682369 13 1.6 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.a7+ Ka8
5.Kb5 Kb7 6.Bd4 Ka8 7.Ka6 b5
864100 13: 2.0 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.a7+ Ka8
5.Kb5 Kb7 6.Bd4 Ka8 7.Ka6 b5
1262935 14 2.8 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka8
5.Bg1 Kb8 6.Be3 Ka8 7.Bd4 Kb8
2723616 14: 5.8 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka8
5.Bg1 Kb8 6.Be3 Ka8 7.Bd4 Kb8
2820170 15 6.0 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka8
5.Bg1 Kb8 6.Be3 Ka8 7.Kc6 Kb8 8.a7+ Ka8
4174275 15: 9.4 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka8
5.Bg1 Kb8 6.Be3 Ka8 7.Kc6 Kb8 8.a7+ Ka8
4304496 16 9.7 +0.20 1.a4 Kb8 2.Bf2 Ka8 3.Kc6 Kb8 4.Kb5 Ka8
5.Bg1 Kb8 6.Be3 Ka8 7.Bf4 Ka7 8.Bc7 Ka8
5028243 16 11.0 +0.20 1.a3 Kb8 2.Kd7 Ka7 3.Kc8 Ka8 4.Bg3 b5
5.Be5 Ka7 6.Kc7 Ka8 7.Kc6 Ka7 8.Bd4+
Kb8 9.a7+ Ka8
5805792 16: 12.9 +0.20 1.a3 Kb8 2.Kd7 Ka7 3.Kc8 Ka8 4.Bg3 b5
5.Be5 Ka7 6.Kc7 Ka8 7.Kc6 Ka7 8.Bd4+
Kb8 9.a7+ Ka8
6107334 17 13.5 +0.20 1.a3 Kb8 2.Kd7 Ka7 3.Kc8 Ka8 4.Bg3 b5
5.Be5 Ka7 6.Kc7 Ka8 7.Kd6 Kb8 8.Kc6+
Ka7 9.Bd4+ Kb8 10.a7+ Ka8
7571773 17: 17.3 +0.20 1.a3 Kb8 2.Kd7 Ka7 3.Kc8 Ka8 4.Bg3 b5
5.Be5 Ka7 6.Kc7 Ka8 7.Kd6 Kb8 8.Kc6+
Ka7 9.Bd4+ Kb8 10.a7+ Ka8
8282772 18 18.8 +0.20 1.a3 Kb8 2.Kd7 Ka7 3.Kc8 Ka8 4.Bg3 b5
5.Be5 Ka7 6.Kc7 Ka8 7.Kc6 Ka7 8.Bd4+
Kb8 9.a7+ Ka8 10.Kb6 b4

_________________
http://sites.google.com/site/gaviotachessengine/

Display posts from previous:

Subject	Author	Date/Time
Position crafty and stockfish both badly mis-evaluate	J. Wesley Cleveland	Thu Jul 29, 2010 8:40 pm
Re: Position crafty and stockfish both badly mis-evaluate	Robert Hyatt	Fri Jul 30, 2010 2:01 am
Re: Position crafty and stockfish both badly mis-evaluate	Sam Hamilton	Fri Jul 30, 2010 2:20 am
Re: Position crafty and stockfish both badly mis-evaluate	J. Wesley Cleveland	Fri Jul 30, 2010 5:16 am
Re: Position crafty and stockfish both badly mis-evaluate	Miguel A. Ballicora	Fri Jul 30, 2010 6:15 am
Re: Position crafty and stockfish both badly mis-evaluate	Ricardo Gibert	Fri Jul 30, 2010 8:58 am
Re: Position crafty and stockfish both badly mis-evaluate	Robert Hyatt	Fri Jul 30, 2010 2:43 pm
Re: Position crafty and stockfish both badly mis-evaluate	Miguel A. Ballicora	Fri Jul 30, 2010 6:06 am
Re: Position crafty and stockfish both badly mis-evaluate	Michel Van den Bergh	Fri Jul 30, 2010 7:29 am
Re: Position crafty and stockfish both badly mis-evaluate	Miguel A. Ballicora	Fri Jul 30, 2010 8:36 am
Re: Position crafty and stockfish both badly mis-evaluate	Sam Hamilton	Fri Jul 30, 2010 3:00 pm
Re: Position crafty and stockfish both badly mis-evaluate	Michel Van den Bergh	Fri Jul 30, 2010 3:49 pm
Re: Position crafty and stockfish both badly mis-evaluate	Richard Vida	Fri Jul 30, 2010 11:15 am

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