Author: Severi Salminen
Date: 14:22:45 12/06/00
Hi!
First a question about history heuristics: Should I clear or decrease the
counters after a search. Now I do nothing. I just add history value to all non
capturing moves and increase the counters by depth if I find a move whose
score>alpha.
How do killers work? More precisely when do I replace a killer move by another?
If I have two killers at each ply with counters should I replace allways the
lowest one? And after the search should I make all ply 1 killers ply 0 killers
and so on?
And then, thanks to all answers about futility pruning. I found a few bugs and
PV code and futility code and now it works a lot better. Below the diagram is
the output:
[D]rnbqkbnr/ppp2ppp/8/3pp3/3PP3/8/PPP2PPP/RNBQKBNR w
Time Depth Score Nodes PV
0.00 1 0.10 136 Be3
0.00 2 0.00 1711 Be3 Be6
0.11 3 0.10 7218 dxe5 dxe4 Bc4
0.44 4 0.01 24742 dxe5 dxe4 Bc4 Nc6
0.77 5 0.10 45588 dxe5 dxe4 Bc4 Qxd1+ Kxd1
1.87 6 0.06 189766 dxe5 dxe4 Bb5+ c6 Qxd8+ Kxd8
3.35 7 0.11 381107 dxe5 dxe4 Qxd8+ Kxd8 Bc4 Nc6 Bf4
12.14 8 0.05 1521228 dxe5 dxe4 Qxd8+ Kxd8 Bc4 Nc6 Bf4 Bb4+
CW: 129 CB: 129 EP: 0
eval: 0.05, nodes: 191295, qnodes: 1329933, NPS: 125307, F: 153159
F means futile moves pruned (total). Without futility pruning I spend about 0.5
s more time and do about 150000 nodes more. Node count is still a bit high, but
it's much less then previously and no more queen sacrifices :)
Severi
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.