Author: James B. Shearer
Date: 21:10:21 10/26/98
Go up one level in this thread
If you do not have square of the pawn code you will make occasional
horrible blunders. Consider the below position in which I had white against a
strong computer (bountyhunter) on ICC. Black plays qc4 converting an easy win
to a embarassing loss as white's lone pawn queens after the queens come off.
This was a blitz game but I tested the position later with rebel 8 and fritz 4
and both like qc4 for a long time. Crafty on the other hand with its square
of the pawn code is never tempted by qc4 as shown by the log file below.
By the way this sort of position illustrates a pet idea of mine. I
think equal time (ignoring alpha beta for the moment) should be spent on
alternative moves (instead of exploring them to the same depth). This can be
done by increasing the depth by the log of the number of alternatives instead of
by a constant amount as you go down the search tree. So for example for forced
moves this is the same as extending by one ply (since log(1) = 0). However this
is more general since in positions like the below, lines after queens are traded
will have fewer choices and thus be explored to greater depth allowing the
search to figure out that qc4 is bad much quicker.
..............................................................................
Crafty v14.10
hash table memory = 12M bytes.
pawn hash table memory = 1.3M bytes.
pondering disabled.
book learning disabled
position learning disabled
noise level set to 0.
White(1): in bherr
White(1): setboard 8/6pp/Q3p3/3p2k1/6q1/P7/8/5K2 b
+---+---+---+---+---+---+---+---+
8 | | | | | | | | |
+---+---+---+---+---+---+---+---+
7 | | | | | | | *P| *P|
+---+---+---+---+---+---+---+---+
6 | Q | | | | *P| | | |
+---+---+---+---+---+---+---+---+
5 | | | | *P| | | *K| |
+---+---+---+---+---+---+---+---+
4 | | | | | | | *Q| |
+---+---+---+---+---+---+---+---+
3 | P | | | | | | | |
+---+---+---+---+---+---+---+---+
2 | | | | | | | | |
+---+---+---+---+---+---+---+---+
1 | | | | | | K | | |
+---+---+---+---+---+---+---+---+
a b c d e f g h
Black(1): exit
Black(1): display
Black(1): analyze
end-game phase
clearing hash tables
time surplus 0.00 time limit 30.00 (3:00)
depth time score variation (1)
1 0.05 4.43 1. ... h5
1-> 1.32 4.43 1. ... h5
2 1.39 4.32 1. ... h5 2. a4
2 1.94 4.42 1. ... Qf5+ 2. Ke2 h5
2-> 2.71 4.42 1. ... Qf5+ 2. Ke2 h5
3 5.38 4.34 1. ... Qf5+ 2. Kg1 h5 3. a4
3 7.27 4.47 1. ... Qf3+ 2. Kg1 Qe3+ 3. Kh2 h5
3-> 9.67 4.47 1. ... Qf3+ 2. Kg1 Qe3+ 3. Kh2 h5
4 16.12 4.36 1. ... Qf3+ 2. Ke1 Qe3+ 3. Kd1 h5 4.
a4
4 20.81 4.51 1. ... Qf5+ 2. Ke2 h5 3. Qb7 g6
4-> 21.67 4.51 1. ... Qf5+ 2. Ke2 h5 3. Qb7 g6
5 32.12 4.47 1. ... Qf5+ 2. Kg2 h5 3. a4 Qe4+ 4.
Kg3 h4+ 5. Kh3
5 48.42 4.51 1. ... h5 2. a4 h4 3. a5 g6
5-> 50.40 4.51 1. ... h5 2. a4 h4 3. a5 g6
6 53.70 4.53 1. ... h5 2. a4 h4 3. a5 Qf3+ 4. Kg1
e5
6-> 56.23 4.53 1. ... h5 2. a4 h4 3. a5 Qf3+ 4. Kg1
e5
7 1:03 4.56 1. ... h5 2. a4 h4 3. Qe2 Qf5+ 4. Qf2
Qb1+ 5. Qe1 Qd3+ <HT>
7-> 1:04 4.56 1. ... h5 2. a4 h4 3. Qe2 Qf5+ 4. Qf2
Qb1+ 5. Qe1 Qd3+ <HT>
8 1:06 4.54 1. ... h5 2. Qe2 Qxe2+ 3. Kxe2 Kf5
4. a4 Ke5 5. a5 Kd6 6. a6 Kc6
8-> 1:13 4.54 1. ... h5 2. Qe2 Qxe2+ 3. Kxe2 Kf5
4. a4 Ke5 5. a5 Kd6 6. a6 Kc6
9 1:21 4.47 1. ... h5 2. Qe2 Qf5+ 3. Kg2 h4 4.
Qe3+ Kh5 5. Qf3+ Kg6 6. Qh3 Qe4+ 7.
Kf2
9-> 2:18 4.47 1. ... h5 2. Qe2 Qf5+ 3. Kg2 h4 4.
Qe3+ Kh5 5. Qf3+ Kg6 6. Qh3 Qe4+ 7.
Kf2
10 3:20 4.61 1. ... h5 2. Qa7 Qf3+ 3. Ke1 g6 4.
a4 Qc3+ 5. Ke2 Qc4+ 6. Ke3 Qc1+ 7.
Kf2 Qd2+ <HT>
10-> 3:38 4.61 1. ... h5 2. Qa7 Qf3+ 3. Ke1 g6 4.
a4 Qc3+ 5. Ke2 Qc4+ 6. Ke3 Qc1+ 7.
Kf2 Qd2+ <HT>
Black(1): exit
Black(1): search qc4
Black(1): analyze
time surplus 0.00 time limit 30.00 (3:00)
depth time score variation (1)
1 0.00 -3.37 1. ... Qc4+ 2. Qxc4 dxc4
1-> 0.01 -3.37 1. ... Qc4+ 2. Qxc4 dxc4
2 0.02 -3.42 1. ... Qc4+ 2. Qxc4 dxc4 3. a4
2-> 0.02 -3.42 1. ... Qc4+ 2. Qxc4 dxc4 3. a4
3 0.03 -3.22 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2
3-> 0.03 -3.22 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2
4 0.04 -2.99 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2
4-> 0.05 -2.99 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2
5 0.07 -2.99 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2 5. Kd2
5-> 0.07 -2.99 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2 5. Kd2
6 0.08 ++ 1. ... Qc4+!!
6-> 0.10 -2.70 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2 5. Kd2
7 0.15 -2.93 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 g6 5. a5 c2 6. Kd2
7-> 0.16 -2.93 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 g6 5. a5 c2 6. Kd2
8 0.18 ++ 1. ... Qc4+!!
8 0.33 -2.63 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2 5. Kd2 h5 6. a5 g6
8-> 0.34 -2.63 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2 5. Kd2 h5 6. a5 g6
9 0.37 ++ 1. ... Qc4+!!
9-> 0.88 -2.34 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 c2 5. Kd2 h5 6. a5 g6
10 3.58 -2.57 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 Kf5 5. a5 g5 6. a6 g4 7. Ke3 h5
10-> 3.60 -2.57 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 Kf5 5. a5 g5 6. a6 g4 7. Ke3 h5
11 5.99 -2.49 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 e5 5. Kd1 e4 6. Kc2 h5 7. Kd1 g6
8. a5
11-> 6.00 -2.49 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 e5 5. Kd1 e4 6. Kc2 h5 7. Kd1 g6
8. a5
12 11.25 -- 1. ... Qc4+
12 16.74 -4.41 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 e5 5. Kd1 e4 6. a5 g6 7. a6 e3
8. a7 c2+ 9. Kxc2 e2 10. Kd2
12-> 16.76 -4.41 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 e5 5. Kd1 e4 6. a5 g6 7. a6 e3
8. a7 c2+ 9. Kxc2 e2 10. Kd2
13 17.65 ++ 1. ... Qc4+!!
13-> 23.06 -4.12 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 c3 4.
Ke2 e5 5. Kd1 e4 6. a5 g6 7. a6 e3
8. a7 c2+ 9. Kxc2 e2 10. Kd2
14 31.46 -- 1. ... Qc4+
14 52.04 -6.34 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 Kf4
4. a5 Ke3 5. Ke1 g5 6. a6 c3 7. Kd1
h5 8. a7 e5 9. a8=Q h4 10. Qd5 Kf4
14-> 52.04 -6.34 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 Kf4
4. a5 Ke3 5. Ke1 g5 6. a6 c3 7. Kd1
h5 8. a7 e5 9. a8=Q h4 10. Qd5 Kf4
15 1:16 -- 1. ... Qc4+
15 2:45 -7.41 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 Kf4
4. a5 Ke3 5. Ke1 g5 6. a6 c3 7. Kd1
h5 8. a7 g4 9. a8=Q Kd3 10. Qh8 c2+
11. Kc1 g3 12. Qxh5
15-> 2:45 -7.41 1. ... Qc4+ 2. Qxc4 dxc4 3. a4 Kf4
4. a5 Ke3 5. Ke1 g5 6. a6 c3 7. Kd1
h5 8. a7 g4 9. a8=Q Kd3 10. Qh8 c2+
11. Kc1 g3 12. Qxh5
Black(1): quit
execution complete.
.............................................................................
James B. Shearer
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Last modified: Thu, 15 Apr 21 08:11:13 -0700
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