Author: Dieter Buerssner
Date: 10:56:52 06/10/05
Go up one level in this thread
On June 10, 2005 at 05:08:02, Uri Blass wrote:
>After
>1...Bxe4
>2.fxe4 f3
>3.e5+ Kd5
>White has no good move but it has only 7 legal moves(not enough even to consider
>using null move pruning in Movei)
I use the same idea. Had to check, what the number of legal moves was, to avoid
null move. It is (nleg > 6) (for this situation). When I change this to nleg >
7, Yace finds Bxe4 an order of magnitude faster.
5149466 5.922 0.68 14t 1...Ba8 2.Bg2 Bb7 3.Bf1 Kc6 4.Ka3 d6 5.Bg2 Kd7
6.Kb2 Ke6 7.Kc1 d5H 8.exd5+H Kxd5H 9.Kd2H Ke5H
{HT}
30072769 34.469 0.69 14t+ 1...Bxe4 2.fxe4 f3 3.e5+ Kd5 4.Ka3 Ke4 5.Kb2
Ke3 6.g5 hxg5 7.Kb1 Kf2 8.Bxc4 bxc4 9.Kc1 d6
10.exd6H Kg2H 11.d7H f2H 12.d8=QH f1=Q+H
13.Kd2H Qf4+H 14.Kd1H {HT} {0}
35057246 40.281 1.08 14++ 1...Bxe4 2.fxe4 f3 3.e5+ Kd5 4.Ka3 Ke4 5.Kb2
Ke3 6.Bxc4 bxc4 7.Kc1 Kf2 8.Kd2 Kf1 9.g5 hxg5
10.Kc1 f2 11.Kd1 d6 12.exd6 g4 13.d7 Kg2
14.d8=Q f1=Q+ 15.Kd2 gxh3 16.Qxh4 {0}
39315875 45.406 1.72 14t 1...Bxe4 2.fxe4 f3 3.g5 hxg5 4.Ka3 Ke5H 5.Kb2H
Kxe4H 6.Bd3+H cxd3H 7.Kc1H d6H 8.Kd2H f2H
9.cxd3+H Kf4H 10.Ke2H f1=Q+H 11.Kxf1H g4H
12.c4H bxc4H 13.dxc4H gxh3H 14.Kg1H h2+H
15.Kxh2H Kg4H 16.c5H dxc5H 17.Kg2H h3+H 18.Kh1H
h2H {HT} {160}
39368963 45.484 1.72 14. 1...Bxe4 2.fxe4 f3 3.g5 hxg5 4.Ka3 Ke5 5.Kb2
Kxe4 6.Bd3+ cxd3 7.Kc1 d6 8.Kd2 f2 9.cxd3+ Kf4
10.Ke2 f1=Q+ 11.Kxf1 g4 12.c4 bxc4 13.dxc4 gxh3
14.Kg1 h2+ 15.Kxh2 Kg4 16.c5 dxc5 17.Kg2 h3+
18.Kh1 h2 {HT} {160}
Of course, this number is not really tuned. I probably decided, that it was
practically impossible to tune it in games, and probably have used some test
suites, to get a rough idea what to use. Finding the number of legal moves is
not a cheap operation in Yace, so I am not using this idea close to the leafs.
Yace will never do a null move, when the side to move has no pieces, but it can
do a null move, when the side has only a minor piece (uses null move with R=1
then, and as always, does some null move verification at reduced depth). I have
changed this back and forth several times, some versions will never do a null
move with only one minor on the board, others can do it for the side with the
minor piece. Also tried to only allow it for B and not for N. No clear results
with either method.
Regards,
Dieter
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