Discussion of chess software programming and technical issues.
Moderators: hgm, Harvey Williamson, bob
Forum rules
This textbox is used to restore diagrams posted with the [d] tag before the upgrade.
-
Uri Blass
- Posts: 8309
- Joined: Wed Mar 08, 2006 11:37 pm
- Location: Tel-Aviv Israel
Post
by Uri Blass » Mon Jun 11, 2007 1:29 pm
I wonder if tord found mate threat extension counter productive or he simply did not try it:
From Glaurng's code:
Code: Select all
Depth extension(Position& pos, Move m, bool pvNode,
bool check, bool singleReply, bool recapture) {
Depth result = Depth(0);
if(check)
result += CheckExtension;
if(singleReply)
result += SingleReplyExtension;
if(pos.move_is_pawn_push_to_7th(m))
result += PawnPushTo7thExtension;
if(pvNode && recapture)
result += RecaptureExtension;
return Min(result, OnePly);
}
-
Tord Romstad
- Posts: 1808
- Joined: Wed Mar 08, 2006 8:19 pm
- Location: Oslo, Norway
Post
by Tord Romstad » Mon Jun 11, 2007 2:43 pm
Uri Blass wrote:I wonder if tord found mate threat extension counter productive or he simply did not try it:
It is simply not implemented yet, just like a lot of other search tricks. Glaurung 2 is still in its early infancy. Whether the mate threat extension helps at all is also a question. I don't recall ever having tested it carefully.
A more interesting difference between Glaurung 1 and Glaurung 2 is that the new version extends recaptures at PV nodes. I tried this several times in Glaurung 1, and it always made the strength drop like a stone. In Glaurung 2, it seems to work (although I have not tested enough to be completely sure). I have no idea why.
Tord