Author: Vasik Rajlich
Date: 00:59:04 01/07/06
Go up one level in this thread
On January 06, 2006 at 16:27:12, Albert Silver wrote: >>>>Your title is misleading so I changed it in my reply. >>>>My opinion is that Rybka searches x+2 plies when it claims to search x plies. >>>> >>>>From my experience it can see at fixed depth of 1 ply things that other programs >>>>see at fixed depth of 3 plies > >Hiarcs sees it in 2 plies, and Chess Tiger 15 sees it in 1. > >>>>Here is an example >>>> >>>>[D]3k2r1/ppb5/3p4/r2N1p2/8/8/1P6/1K2RB1R b - - 0 1 > >Analysis by Hiarcs 7.32: > >1...Rxd5 > -+ (-3.62) Depth: 1 00:00:00 >1...Rxd5 2.Bc4 > -+ (-3.29) Depth: 2/4 00:00:00 >1...Rxd5 2.Bc4 Ba5 3.Bxd5 Bxe1 4.Bxg8 > +- (2.07) Depth: 2/5 00:00:00 >1...a6 2.Bc4 > ± (0.74) Depth: 2/7 00:00:00 >1...Rf8 2.Bc4 > ² (0.67) Depth: 2/11 00:00:00 >1...Bb6 2.Nxb6 axb6 > ² (0.55) Depth: 2/11 00:00:00 > > >Analysis by Chess Tiger 15.0: > >1...Rxd5 > ² (0.30) Depth: 1 00:00:00 >1...Rxd5 > -+ (-3.12) Depth: 1 00:00:00 >1...Rxd5 > +- (2.74) Depth: 1 00:00:00 >1...f4 2.Nxf4 > +- (1.80) Depth: 1 00:00:00 >1...Rg3 > ± (1.14) Depth: 1 00:00:00 >1...Rc5 > ± (1.10) Depth: 1 00:00:00 >1...Rc5 2.Nf6 > ± (0.92) Depth: 2 00:00:00 >1...Rc5 2.Nf4 Re5 > ± (1.08) Depth: 3 00:00:00 1kN > >(Silver, Private 06.01.2006) > Very nice - my hat is off to Christophe. It's a pity that Tiger development seems to have stopped. Vas > >[D]3k2r1/pp1b4/3p4/r2N1p2/8/8/1P6/1K2RB1R b - - 0 1 > >Analysis by Hiarcs 7.32: > >1...Rxd5 > -+ (-3.79) Depth: 1 00:00:00 >1...Rxd5 2.Bc4 > -+ (-3.45) Depth: 2/4 00:00:00 >1...Rxd5 2.Bc4 Bc6 3.Bxd5 Bxd5 > -+ (-2.07) Depth: 2/5 00:00:00 >1...Rxd5 2.Bc4 Bc6 3.Bxd5 Bxd5 > -+ (-2.07) Depth: 3/10 00:00:00 > > >Analysis by Chess Tiger 15.0: > >1...Rxd5 > ² (0.32) Depth: 1 00:00:00 >1...Rxd5 > -+ (-3.04) Depth: 1 00:00:00 >1...Rxd5 > µ (-0.94) Depth: 1 00:00:00 >1...Rxd5 2.Bc4 > µ (-0.94) Depth: 2 00:00:00 >1...Rxd5 2.Bc4 Bc6 3.Bxd5 Bxd5 > µ (-0.94) Depth: 3 00:00:00 >1...Rxd5 2.Bc4 Bc6 3.Bxd5 Bxd5 > µ (-0.94) Depth: 4 00:00:00 >1...Rxd5 2.Bc4 Bc6 3.Bxd5 Bxd5 > µ (-0.94) Depth: 5 00:00:00 1kN >1...Rxd5 2.Bc4 Bc6 3.Rh6 Kd7 4.Rh7+ Kd8 5.Bxd5 Bxd5 > ³ (-0.52) Depth: 6 00:00:00 2kN > > > Albert > >>>> >>>>Rybka does not capture the knight at depth 1 in the first case but capture the >>>>knight ar depth 1 in the second case. >>>> >>>>Can Vasik explain why? >>>> >>>>evaluation? >>>>I do not believe it. >>>> >>>>It must be search and rybka search after Rxd5 Bc4 black move and see that in the >>>>first case no move save black from a loss of full rook when in the second case >>>>it searches Rxd5 Bc4 Bc6 >>>> >>>>Uri >>>Hi all, >>> >>>It's clearly seen that Rybka uses some form of selective search different from >>>others' in the quescence search which is not a full width search, therefore is >>>not counted in nps. This explains the low nps, Rybka does extra work in the QS >>>which pays off. >>>Obvious, that a usual 1 ply search cannot be such better even with a superb >>>evaluation but a Rybka-type can be. >>> >>>Regards, >>>László >> >>No >> >>It is not clear >> >>I can achieve the same effect by not counting nodes in the qsearch and writing >>depth x when the real depth is x+2 >> >>It is possible that rybka does nothing special except playing better when vasik >>tries to hide what it does by misleading information. >> >>Uri >>Uri
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