Author: Uri Blass
Date: 07:13:58 05/21/01
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On May 21, 2001 at 08:58:41, José Carlos wrote: >On May 21, 2001 at 06:52:52, Uri Blass wrote: > >>This position could happen in kasparov-Deeper blue but kasparov did not play >>40.gxh5 >> >>Based on Deeper blue logfiles we know that Deeper blue evaluated the position >>as 0.5 pawn advantage for white at depth 9(6)=15 >> >>Crafty's evaluation at depth 15 is 2.93 pawns for white so we can see that the >>difference in evaluation is 2.43 pawns. >> >>Part of the difference can be explained by different evaluation but most of the >>difference is clearly because of the fact that Crafty can see more than Deeper >>blue. >> >>Deeper blue found the line 40...Bxh5 41.Rh1 only at depth 10(6)=16 when Crafty >>could see it at depth 14 and the line was not changed at the next 2 plies. >> >>Crafty can see the line 40...Bxh5 41.Rh1 Bf3 42.Rg1 Bh5 43.g7 Nf3 44.Rg3 c5 >>45.bxc5 Rc8 46.f6 Rxc5 at depth 15 and 16 when Deeper blue can see it only at >>depth 17,18(deeper blue can see a different line but the difference is only >>41...Kg5 42.Rg1 Kh6 that leads to the same position as 41..Bf3 42.Rg1 Bh5 and >>moves 43-46 are the same. >> >>It seems that Crafty is a very good program and it can outsearch deeper blue by >>2 plies. >> >>I do not know the meaning of the plies of deeper blue but it seems to be not >>brute force search. >> >>I also doubt if deeper blue could search 200M nodes per second otherwise I >>cannot understand the reason that it is outsearched by other top programs again >>and again based on the pv's >> >>It is possible that the claims about 200M nodes per second were only a >>psychological war against kasparov >> >>Here is the analysis of Crafty >[snip] > > Not sure what you mean. If, for example, I choose not to prune at all and >extend a lot, I'll see more than anyone at the same depth. The problem is that >I'll never reach the same depth as the rest with the same time. > So, maybe Crafty sees more at the same depth, but that means nothing. The >right comparison would be > >who sees more _with the same time_? > > José C. The point is that the claim about deeper blue was that deeper blue did more extensions than other programs and no pruning(at least no null move pruning). It is clear that Crafty can see deeper with the same number of nodes that deeper blue searched. If you talk about the same time than it is dependent on the hardware and deeper blue could see deeper than Crafty(p800) but it seems that Crafty on good alpha could see deeper than deeper blue. Deeper blue seems to be only 2-7 times faster based on the relevant position. The time that deeper blue got depth 10(6)=16 is 27 seconds to fail low and 65 seconds to solve the fail low when Crafty got depth 14 that is eqvivalent based on the main line after 179 seconds. 179/27 is the biggest estimate for the speed ratio based on the relevant position The time that deeper blue got depth 11(6)=17 is 229 seconds when Crafty could get similiar main line at depth 15 after 536 seconds. 536/229 is the smallest estimate for the speed difference based on the relevant position. Uri
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