Author: Stuart Cracraft
Date: 12:54:09 08/22/04
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On August 22, 2004 at 04:00:53, Uri Blass wrote: >On August 21, 2004 at 23:56:48, Stuart Cracraft wrote: > >>On August 21, 2004 at 23:39:17, Stuart Cracraft wrote: >> >>>There was an error. The right position is: >>> >>>[D]5r1k/6p1/1n2Q2p/4p3/8/7P/PP4PK/R1B1q3 w >>> >> >>It takes my program 142M nodes to get the right move for the >>right reason in 10 minutes. This would be about 1.5 minutes >>on a more modern PC. >> >>I am wondering, specifically, what tricks there are to get it >>solved faster than this on non-parallel. >> >>Stuart > >What about check extensions and check in the qsearch? > >What is your main problem >seeing that Qxb6 has negative evaluation or seeing that Bxh6 has better >evaluation than Qxb6 > >In order to see that Qxb6 is losing >You need to see the following line > >1.Qxb6 Rf1 2.Qd8+ Kh7 3.Qd3+ e4 4.Qxx Qh1# > >4...Qh1# is move that my qsearch detects so even without check extensions it >seems to be only 7 plies of search >2.Qd8+ and 3.Qd3+ are extended by 1 ply so I can see that 1.Qxb6 is losing the >queen in 5 plies(the evaluation is only slightly behind 0 at this point) > >If you want to see that Bxh6 is at least a draw for white then check extensions >may also help because white has a perpetual check but a lot of checks. > >You can use the botvinik extension that is doing partial extensions for >threating the same piece move after move when the same piece may be also the >king. > >I use the botvinik extension today only for checks. > >Uri Haven't heard of this one. Sounds interesting. So how do you tell that you're threatening the same piece move after move? At what point do you make that decision and grant the partial extension? (fractional same thing?) Stuart
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