Author: Johan de Koning
Date: 00:13:13 09/29/03
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On September 28, 2003 at 16:00:43, Tim Foden wrote: >On September 26, 2003 at 18:26:17, Johan de Koning wrote: >>1. d4? d5? 2.g4 wins (see the earlier d4d5 run) >>1. d4? b5! draws (see D29) >>1. c4 mate in 19 or 18 >>1. b4 mate in 18 >>Assuming no bugs of course. >> >>... Johan > >:) That wasn't intended to be funny! Shortly after my post I did discover a bug. Similar to yours, in the "ancient" first optimization heuristic. /**/ if( OppoReachedRank7() ) return -MATE(d + 2); /**/ if( OnlyMeStalemate() ) return -MATE(d ); The first if can return a score that should be treated as an upper bound until the stale is resolved and possibly returned a worse score. Of course it won't affect the outcome of the game, and of course the first line became redundant after the more aggressive full passer heuristic. BTW, I also tried a-h mirroring in the TT (yes, including move and ep :-). On d4d5 and 7-7 the difference was below noise level, as expected. On the initial position the total time improved from 1.27 to 1 day, with the node counts of course improving a few % more. Not very impressive. And that's because (I guess) mirrored positions are miles apart in the search tree and don't live long enough in the always-replace fork of the TT. The depth-preferred fork did a good job however: the occasionally observed current lines never started with e,f,g,h. Anyway, I think I'll skip the experiment with fully normalized TT entries. (That's with inactive files removed, and the remaining files flipped/sorted into canonical form). That would be good for a complete retrograde analysis, but it won't beat alpha-beta on a fixed starting position. >Thanks for this. My secondary machine (Duron 800MHz) is now free from playing >matches for a few days, so maybe I'll run mine on it for a couple of days and >see if I get the same result. Since the search is magnitudes larger than the TT, the size of the TT is pretty important here. (I'm not going into exact models and equations right now. :-) If your Duron has lots of RAM it's worth a try. However if it has less than your XP1666, my guess is that 3 Duron days won't beat 1 XP night. Anyway, have fun but don't forget to enjoy your real work. :-) ... Johan PS: sorry for the long blah blah. I just wanted to put my pending thoughts on record before forgetting them. :-)
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