Author: Uri Blass
Date: 04:36:53 05/20/03
Go up one level in this thread
On May 20, 2003 at 07:18:42, Uri Blass wrote: >On May 20, 2003 at 06:22:22, Uri Blass wrote: > >>On May 20, 2003 at 03:50:58, Tony Werten wrote: >> >>>On May 20, 2003 at 02:17:14, Tim Foden wrote: >>> >>>>On May 19, 2003 at 23:46:58, Will Singleton wrote: >>>> >>>>>I was trying to figure out why my latest build doesn't do quite as well on >>>>>ecm86, and I ran Ruffian on it. To my surprise, Ruffian couldn't solve it, even >>>>>given 5 minutes. This is odd, since most other progs can do it in less than 10 >>>>>seconds. (What I take away from this exercise is that my program must now be >>>>>stronger. Otherwise, I'd have to work on the problem, which is much less >>>>>interesting than testing new ideas.) >>>>> >>>>>[D]2r3k1/1nqbrp2/p5pp/1p1Pp1N1/8/1P5P/P1B2PP1/2RQR1K1 w - - >>>> >>>>I would assume then (from running Green Light), that Nxf7 is the correct move >>>>here? >>>> >>>>The PV is interesting as it contains 9 captures in a row at the start of the PV. >>>> Maybe ruffian is pruning if there are more than a certain number of captures in >>>>a row (as this is very unlikely to be a good thing). >>> >>>My guess is that Ruffian is a preprocessor, which can't handle 9 captures >>>because the position is so different ( root position compared to leaf position ) >>> >>>There is a good chance Fritz 5.32 will show the same beheavior. >>> >>>Tony >> >>Your guess seems to be wrong and if I do the moves Nxf7 Rxf7 and take them back >>Ruffian has no problem to find Nxf7. >> >>Fritz5.32 also has no problem with that move. >>I believe that being preprocessor is a bad idea so my default assumption(unless >>other things are provedO) is that Ruffian is not a preprocessor. >> >>I guess that some pruning that is not null move pruning prevents it to see Nxf7 >>in a reasonable time. >> >>Uri > >Note also that if I give Ruffian an hour to analyze then it can see Nxf7 > >depth=16 +1.75 Nxf7 Rxf7 Bxg6 Qxc1 Bxf7+ Kxf7 Qh5+ Kg7 Qxe5+ Kg6 Rxc1 Rxc1+ Kh2 >Rc8 Qe3 Nc5 b4 Na4 Qa7 Rd8 Qxa6+ Kg5 >Nodes: 1393992604 NPS: 406222 >Time: 00:57:11.60 > >Uri Ruffian shows draw score after the 9 captures and they are the wrong reason to play Nxf7. The right line is movei's line with Qh5+ that is the same as ruffian line. The main reason that Ruffian does not see the solution in a small time is probably different evaluation and it seems that Ruffian underevaluate the queen in the right line. [D]2r3k1/1nqb1r2/p5pp/1p1Pp3/8/1P5P/P1B2PP1/2RQR1K1 w - - 0 1 After the first 2 moves(Nxf7 Rxf7) Ruffian starts to see significant advantage only at depth 12: 10456 <first : 10 45 135 841233 Bxg6 Qxc1 Bxf7+ Kxf7 Qxc1 Rxc1 Rxc1 Nd6 Rc7 Ke8 Ra7 Bc8 11827 <first : 11 51 273 1653191 Bxg6 Qxc1 Bxf7+ Kxf7 Qh5+ Kg7 Qxe5+ Kg6 Rxc1 Rxc1+ Kh2 Rc2 Qe7 Bc8 Qe8+ Kf6 Kg3 13780 <first : 12 86 468 2764242 Bxg6 13780 <first : ++ 15292 <first : 12 100 619 3652907 Bxg6 Qxc1 Bxf7+ Kxf7 Qh5+ Kg7 Qxe5+ Kg6 Rxc1 Rxc1+ Kh2 Rc8 Qe7 Rd8 Kg3 Kf5 Qh7+ Kg5 Uri
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.