Author: Tony Werten
Date: 08:01:36 04/22/04
Go up one level in this thread
On April 21, 2004 at 03:30:03, Tony Werten wrote: >On April 20, 2004 at 12:42:14, Tord Romstad wrote: > >>On April 20, 2004 at 07:45:16, Sune Fischer wrote: >> >>>>>>>2. Don't make a null move if the static eval is far below beta. >>>>>> >>>>>>Actually, you can drop 2 as well :) >>>>>> >>>>>>Move ordering is much better if you just nullmove everywhere. That way, you can >>>>>>also throw out IID. >>>> >>>>That's not my experience. Nullmoving everywhere doesn't noticably improve >>>>my move ordering, and it increases the size of the game tree (by around >>>>15-20%, if I recall correctly). Throwing out IID doesn't help. >>>> >>>>Perhaps this depends on how your move ordering works. >>> >>>Number 2 doesn't seem to work for me either, I think the explanation is rather >>>simple. A nullmove is relative cheap, if I detect correctly 75% of the time that >>>a nullmove is futile, then that still means I detect it wrong 25% of the time. >>>As it turns out these 3 savings of a nullmove doesn't outweigh the 1 full search >>>which could have produced a fast cutoff. >>>The end result is a bigger tree for me. >>> >>>In principle it can work, but you must be very accurate in guessing when not to >>>nullmove because a full search is very expensive. >> >>I do some static threat detection in my eval. Perhaps this is why this >>works better for me than for you and Tony. > >I have a full static mate detection wich can detect up to mate in 7. I call it >for side to move. > >Calling it for side not to move seems to be more expensive than just doing a >nullmove. Duh, after the nullmove, sides have swapped, so I basicly call it for side not to move, just one ply later. If I call it before nullmove, most of the time I would end up doing it twice in a row, wich is too expensive (or I should hash it, hmm yet another hashtable ?). Tony > >Tony >
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