Author: Sune Fischer
Date: 13:21:23 02/10/03
I'm fooling around with some root node aspiration search,
Looks like it is a tad unstable, I wonder if that is normal.
It produces different preferred moves at different plies.
E.g. normally it prefers e4 at ply 11, but using a narrow window of 0.1 pawn it
prefers e4 already at ply 9. Sure the hashtable is going to make a difference
here, I realize that, but still a change on the root move is not an
insignificant effect.
The narrower the window, the more instability. Is this to be expected?
the code:
window = param::pawn_unit/10;
walpha = previous_score-window;
wbeta = previous_score+window;
score = -b.Search(1,ONEPLY*(maxdepth-1),-wbeta,-walpha,0);
if (score <= walpha) {
score = -b.Search(1,ONEPLY*(maxdepth-1),-wbeta,-alpha,0);
if (score >= wbeta)
score = -b.Search(1,ONEPLY*(maxdepth-1),-beta,-alpha,0);
} else if (score >= wbeta) {
score = -b.Search(1,ONEPLY*(maxdepth-1),-beta,-walpha,0);
if (score <= walpha)
score = -b.Search(1,ONEPLY*(maxdepth-1),-beta,-alpha,0);
}
results of different window widths:
window=pawn_unit:
1 -1 0 1 1.a3
1 14 1 5 1.d3
1 23 1 14 1.d4
1 105 1 21 1.Nc3
2 -103 1 52 1.Nc3 Nf3
2 0 2 96 1.Nf3 Nf6
3 103 2 280 1.Nf3 Nf6 2.Nc3
4 -23 2 507 1.Nf3 Nc3
4 23 3 1535 1.Nc3 Nf6 2.Nf3
5 23 3 1711 1.Nc3 Nf6 2.Nf3
6 0 4 2781 1.Nc3 Nf6 2.Nf3 Nc6 3.e4 e5
7 16 5 7890 1.Nc3 Nf6 2.Nf3 Nc6 3.d4 d5 4.Bf4
8 6 6 14544 1.Nc3 Nf6 2.Nf3 Nc6 3.e4 d5 4.e5 Ng4
9 15 33 197084 1.Nc3 d5 2.Nf3 Nc6
10 8 66 439047 1.Nc3 Nf6 2.e4 e5 3.Nf3 Nc6
11 12 234 1641245 1.Nc3 Nf6 2.Nf3 Nc6 3.d4 d5 4.e3 Bf5 5.Bd3 Bxd3 6.Qxd3
11 15 597 4247723 1.e4 e5 2.Nf3 Nc6
12 12 992 7037705 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Bb5 exd4
13 14 2475 17533424 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Bb5 Nd4 5.O-O Bc5 6.Nxe5 Nxb5
7.Nxb5 Nxe4
14 14 3768 26153111 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Bb5 Nd4 5.O-O Bc5 6.Nxe5 Nxb5
7.Nxb5 Nxe4
window=pawn_unit/10:
1 -1 0 1 1.a3
1 14 1 5 1.d3
1 23 1 14 1.d4
1 105 1 21 1.Nc3
2 -103 2 52 1.Nc3 Nf3
2 0 2 96 1.Nf3 Nf6
3 103 2 272 1.Nf3 Nf6 2.Nc3
4 -23 2 489 1.Nf3 Nc3
4 23 3 1517 1.Nc3 Nf6 2.Nf3
5 23 3 1693 1.Nc3 Nf6 2.Nf3
6 -16 4 3765 1.Nc3 Nf3
6 16 4 4367 1.Nf3 Nf6 2.Nc3
7 16 5 8324 1.Nf3 Nf6 2.Nc3
8 6 7 15958 1.Nf3 Nf6 2.Nc3 Nc6 3.e4 d5 4.e5 Ng4 5.Nxe4
9 15 21 112696 1.Nf3 Nf6 2.Nc3 d5 3.d4 Nc6 4.Bf4 Bf5 5.e3
9 17 41 249717 1.e4 Nc6 2.Nc3 Nf6 3.Nf3 d5 4.exd5 Nxd5 5.Bd3
10 8 110 729380 1.e4 Nf6 2.Nc3 e5 3.Nf3 Nc6 4.Nc3
11 15 392 2758226 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.Bxc6 dxc6 5.Nc3 Bd6 6.O-O
12 12 740 5225754 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Bb5 Bd6 5.O-O a6 6.Bxc6 dxc6
13 14 2689 19137433 1.e4 e5 2.Nc3 Nf6 3.Nf3
14 14 3521 25053272 1.e4 e5 2.Nc3 Nf6 3.Nf3
window=pawn_unit/100: (pawn_unit=1000)
1 -1 0 1 1.a3
1 14 0 5 1.d3
1 23 0 14 1.d4
1 105 1 21 1.Nc3
2 -206 1 49 1.Nc3 Nf3
2 0 1 93 1.Nf3 Nf6
3 103 1 271 1.Nf3 Nf6 2.Nc3
4 -23 2 553 1.Nf3 Nc3
4 23 2 1629 1.Nc3 Nf6 2.Nf3
5 23 2 1803 1.Nc3 Nf6 2.Nf3
6 -16 3 3382 1.Nc3 Nf3
6 16 4 3829 1.Nf3 Nf6 2.Nc3
7 16 4 7702 1.Nf3 Nf6 2.Nc3
8 -15 7 26519 1.Nf3 Nc3
8 -11 10 37593 1.a3 Nf6 2.Nc3 Nc6 3.Nf3 d5 4.d4 Bf5 5.Nxe4
8 17 15 76685 1.e4 Nf6 2.Nc3 Nc6 3.Nf3
9 17 31 185188 1.e4 d5 2.Nc3 Nf6
10 -24 86 596412 1.e4 exd5
10 0 106 742042 1.d4 d5 2.Nc3 Nf6 3.Nf3 Nc6 4.Bf4 Bf5 5.Nb5 Rc8 6.Nxe5
10 8 161 1149018 1.Nc3 Nf6 2.e4 e5 3.Nf3 Nc6
11 12 347 2482318 1.Nc3 Nf6 2.Nf3 Nc6 3.d4 d5 4.e3 Bf5 5.Bd3 Bxd3 6.Qxd3
11 15 658 4712297 1.e4 e5 2.Nf3 Nc6
12 -14 1006 7183908 1.e4 Nc3
12 14 1222 8702636 1.Nc3 Nf6 2.Nf3 Nc6 3.e4 e5
13 14 1970 14002541 1.Nc3 Nf6 2.Nf3 Nc6 3.e4 e5
14 14 3647 25603089 1.Nc3 Nf6 2.Nf3 Nc6 3.e4 e5
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