Author: Robert Hyatt
Date: 10:38:52 01/26/00
Go up one level in this thread
On January 26, 2000 at 12:36:23, Sune Larsson wrote: >On January 26, 2000 at 12:02:47, Côme wrote: > >> >> >>Hello, >> >>[D]r1b1r1k1/p1q1pp2/2p4p/1p4pn/5b1B/2PBNN2/PP2Q1PP/R4RK1 w - - >> >>Fritz 6 don't find Nxg5 after 3 min on my K6 II 350 ! >>Crafty don't find Nxg5 after 5 min on my K6 II 350 ! >>BUT Hiarcs and Junior find Nxg5 in a couple of sec . >> >>Can you test others programs ? >> >>Best Regards >>Alexandre Côme > > Hello Come! > > Nice to see you back in action! After about 30 sec Nimzo 7.32 /the dangerous >version :)/ wants to play > 1.Be1 with the eval +-1.54 (white is a piece up). Nimzo also gives > 1.Nxg5 Bxh2+ 2.Kh1 Nf4 3.Qf3 hxg5 with +0.36 > > Regards > Sune Let it search longer. Nxg5 is crushing. If I let crafty search to depth=12, I get Be1, +1.60, but if I tell it to only search Nxg5, by the time it gets to 12 plies the score is +3.6. I haven't looked at it yet, but in general, a PV that starts off with a sacrifice and doesn't recover the material until way into the search, is a type of position that kills a null-move search. The problem is that after Nxg5, white is down a piece for a couple of pawns, while after Be1 white is up well over a pawn. After searching anything below Nxg5, when trying a null-move search for the opponent it will always fail high, as the depth reduction hides the win of the material that happens very deep. And it makes the sacrifice look foolish. This is "just one of those null-move problems". Little to be done about it in reality...
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