Author: Dann Corbit
Date: 22:31:19 09/23/99
Go up one level in this thread
On September 24, 1999 at 00:45:45, Steve Maughan wrote:
>I gave Nimzo 7.32 the following test position
>
>r2b1qrk/ppp3pp/3p1p2/4pPPQ/4P2P/3PB3/PPP5/1K4RR w - - 0 1
>
>It's mate in 4 via 1.Qxh7+ Kxh7 2.g6+ Kh8 3.Rg5 fxg5 4.hxg5 mate. The position
>is simple for todays programs to solve.
>
>However giving Nimzo the white pieces it immediately announces mate in 2!! Now
>I can accept that it is reasonable to announce mate in more than 4, but not
>less. Also after playing 2.g6 it announces mate in 1, and then after Rg5 and
>hxg5 it claims mate in 0.
>
>I assume that this is a minor bug in the engine. It really should be sorted out
>as it means that Nimzo cannot be trusted to give shortest mates.
As a rule, chess engines cannot be trusted to give shortest mates. That job
goes to mate finders.
It is clearly a bug in the engine. It also casts aspersions on test results
with that engine if Nimzo announces a mate and the other engine does not see it.
I suggest that you notify the manufacturer.
Here is the output of the mate finder Chest:
H:\foobart\sub\Release>chest < a
CHEST version 3.15, 28-Dec-1998
Options =
Input file: STDIN
Reading job:
W: Kb1 Qh5 Rg1 Rh1 Be3 Pa2 Pb2 Pc2 Pd3 Pe4 Pf5 Pg5 Ph4 (13)
B: Kh8 Qf8 Ra8 Rg8 Bd8 Pa7 Pb7 Pc7 Pd6 Pe5 Pf6 Pg7 Ph7 (13)
FEN: r2b1qrk/ppp3pp/3p1p2/4pPPQ/4P2P/3PB3/PPP5/1K4RR w - -
analysing (mate in 4 moves):
Solution (in 4 moves):
Qh5 : h7
refu 1: Qh7:+ Kh7: [ 2-]
solu 6: Kh7: [ 3+]
refu 2: g6 h6 [ 3-]
solu 1: Qf7 [ 1+]
solu 2: Rb8 [ 1+]
solu 3: Rc8 [ 1+]
refu 3: gf6 Qf7 [ 3-]
refu 4: d4 Qf7 [ 3-]
refu 5: c3 Qf7 [ 3-]
refu 6: c4 Rc8 [ 3-]
solu 4: fg5 [ 2+]
refu 7: b3 Qf7 [ 3-]
refu 8: b4 Qf7 [ 3-]
refu 9: a3 Qf7 [ 3-]
refu 10: a4 Qf7 [ 3-]
refu 11: Bf4 Qf7 [ 3-]
refu 12: Bd2 Qf7 [ 3-]
refu 13: Bc1 Qf7 [ 3-]
refu 14: Bf2 Qf7 [ 3-]
refu 15: Bd4 Qf7 [ 3-]
refu 16: Bc5 Qf7 [ 3-]
refu 17: Bb6 Qf7 [ 3-]
refu 18: Ba7: Qf7 [ 3-]
refu 19: Rh2 Qf7 [ 3-]
refu 20: Rh3 Qf7 [ 3-]
refu 21: Rf1 Qf7 [ 3-]
refu 22: Re1 Qf7 [ 3-]
refu 23: Rd1 Qf7 [ 3-]
refu 24: Rc1 Qf7 [ 3-]
refu 25: Rg2 Qf7 [ 3-]
refu 26: Rg3 Qf7 [ 3-]
refu 27: Rg4 Qf7 [ 3-]
refu 28: Qh6 Qf7 [ 3-]
refu 29: Qg4 Qf7 [ 3-]
refu 30: Qf3 Qf7 [ 3-]
refu 31: Qe2 Qf7 [ 3-]
refu 32: Qd1 Qf7 [ 3-]
refu 33: Qg6 Qf7 [ 3-]
refu 34: Qf7 Qf7: [ 3-]
refu 35: Qe8 Qf7 [ 3-]
refu 36: Kc1 Rb8 [ 3-]
solu 5: fg5 [ 2+]
refu 37: Ka1 Qf7 [ 3-]
Time (user) = 1.00 sec
Reading job:
BTW, Crafty also finds it.
PFGA: EPD record: 1
middle-game phase
clearing hash tables
time surplus 0.00 time limit 600:00 (600:00)
nss depth time score variation (1)
White(1): exit
5 0.18 Mat04 1. Qxh7+ Kxh7 2. g6+ Kh8 3. Rg5 fxg5
4. hxg5#
5-> 0.18 Mat04 1. Qxh7+ Kxh7 2. g6+ Kh8 3. Rg5 fxg5
4. hxg5#
6 0.20 Mat04 1. Qxh7+ Kxh7 2. g6+ Kh8 3. Rg5 fxg5
4. hxg5#
6-> 0.22 Mat04 1. Qxh7+ Kxh7 2. g6+ Kh8 3. Rg5 fxg5
4. hxg5#
7 0.23 Mat04 1. Qxh7+ Kxh7 2. g6+ Kh8 3. Rg5 fxg5
4. hxg5#
7-> 0.26 Mat04 1. Qxh7+ Kxh7 2. g6+ Kh8 3. Rg5 fxg5
4. hxg5#
time=0.26 cpu=100% mat=0 n=41489 fh=94% nps=159573
ext-> checks=831 recaps=239 pawns=149 1rep=288 thrt:80
predicted=0 nodes=41489 evals=6575
endgame tablebase-> probes done=0 successful=0
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