Author: Robert Hyatt
Date: 18:28:36 01/14/98
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On January 14, 1998 at 17:26:37, Stuart Cracraft wrote: >On January 13, 1998 at 20:37:29, Robert Hyatt wrote: > >>the one that lasted. I don't do it in Crafty, however. Although I >>probably >>do too many others... > >Bob, > >Off the top of your head, can you list the Crafty extensions that you >remember? Are some of these more tentative than others? Are any clearly >experimental? Which are the most helpful extensions in terms of >strength? > >Thanks, >Stuart Yes. I have five at present: 1. check. If I make a move that checks the opponent at the next ply, I extend 3/4 ply. I extend when I check, rather than the next ply when I get out, because I have a "checkless" q-search. This way, if I check, I extend, and go maybe 1 ply deeper, rather than checking and dropping into the q-search, which could not extend at all. This is commonly called the "out of check" extension. 2. one-legal-move. If I reach a position where there is only one legal move, and I'm in check (obviously) then I extend 3/4 ply here too. 3. pushing passed pawns, when the push is safe, and the material is reduced enough to call this an endgame, I extend 3/4 ply. 4. recapture. When I capture the piece that moved at the last ply, and that move was also a capture, and the material balance hasn't changed, I extend 3/4 ply (even exchange extension). 5. bruce's Mate threat extension is also done (3/4 ply) at any one ply, extensions can be added, but can not total more than one ply.
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