Author: Robert Hyatt
Date: 06:32:55 10/05/98
Go up one level in this thread
On October 05, 1998 at 01:23:56, Roberto Waldteufel wrote: > >On October 04, 1998 at 23:29:46, Robert Hyatt wrote: > >>On October 04, 1998 at 21:21:09, Roberto Waldteufel wrote: >> >>> >>>On October 04, 1998 at 20:24:08, Will Singleton wrote: >>> >>>>On October 04, 1998 at 19:06:15, Roberto Waldteufel wrote: >>>> >>>>> >>>>>Hi all, >>>>> >>>>>I wonder what reductions various programs use for the null move. I reduce by two >>>>>plies, but I believe a one-ply reduction may be more usual. However, I have >>>>>found R=2 produces quite good results in my program. I would like to hear of >>>>>others' experiences. >>>>> >>>>>Best wishes, >>>>>Roberto >>>> >>>> >>>>Amateur uses r=2, and gets about a ply deeper on average. But I've noticed that >>>>in positions where there is a clear better move, the node reduction is great, >>>>and in positions where there is no clear cut better move, the reduction is not >>>>that great. Of course, you need it most in the latter situation. I'm probably >>>>doing something wrong. Do you notice anything similar? >>>> >>>>Will >>> >>>Yes, I have noticed more improvement when one move is clearly best than when >>>there are many plausible candidates, but I had put that down to the nature of >>>the null move! If there are many plausible moves, then that leaves fewer >>>terrible moves to cause null-move cutoffs on the next ply. Do you find the same >>>effect with R=1 as with R=2? I suspect that nodes with a clearly best move are >>>just plain easier to handle than the rest. >>> >>>Best wishes, >>>Roberto >> >> >>null move, R=2, works well and has been used in crafty for several years >>now. But it does cause problems, and definitely won't work if your >>machine is slow, because depths of 5-6 will crash and burn when you use >>null-move. The deeper the search, the safer this becomes, and I haven't >>seen null-move related losses in a couple of years now. But early on,I >>certainly did... particular in "the" positions like black has castled >>kingside, played g6, and white gets in Qh6 and bishop/pawn on f6... the >>null-move can hide the resulting mate... > >I havn't noticed anything like this yet, but I've only been using null move a >short while, and I did receive a game where Rabbit blundered material in a blitz >game, but I think this has more to do with the programs poor performance at very >fast time controls than null move. I'll keep an eye out for any bad side >effects, but so far I have seen none besides this one case, and my search is >faster :-) Do you disable null move for blitz, or if you know Crafty is going to >be competing on slow hardware? > >Roberto I don't turn it off depending on the speed of the machine, no. I simply assume "normal" hardware today. On the P6, I generally see searches that go 7-8 plies minimum, which will "hide" the bug quite effectively for the most part. If I were seeing 4-5 or maybe even 6 plies, I would have more problems...
This page took 0 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.