Author: Frank Phillips
Date: 13:33:13 01/10/03
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On January 10, 2003 at 13:19:30, Dieter Buerssner wrote: >On January 10, 2003 at 12:54:02, Frank Phillips wrote: > >>Thanks for the suggestions. In fact I tried all those things. No hash, no >>extentions and no (hash + no extensions). >> >>After 1 hour 15 mins (of normal engine configuration) I have Re3+ and +0.65. > >Do you mean +0.65 for black or for white? If for some reason (which I could not >understand) your engines evalutes black better, you won't see it. Also, do you >give 0.0 for the first repetition (at least deeper in the tree)? If not, it will >proablaby be too deep. As Uri said, switching off extensions, will hurt. You >could switch off any extensions beside check. With 1 ply extension for check, >the line should be about 11 ply deep. I did not think carefully about it, but >null move may delay things. The "silent" move Kd2 will be needed, after which >null move may fail high with not enough depth. Also you might want to try to >start a little bit later in the line I have given. It should almost be possible, >to investigate the problem by a search tree dump (but a lot of work ...). > >>Here is a similar one I cannot get either. It have come from CCC, but I cannot >>remember. >> 7k/4QP2/7p/6rP/8/1K6/6r1/8 b - - > >I get 0.0 after 30 seconds at ply 14 (P4, 2.53 GHz). This one is harder for Yace >than the above one. > >Good luck, >Dieter + means white is ahead. I count as 3 rep. any position that has occurred three times in the (game+search) and any position that has occurred before in the search - so I only need 1 rep in the search. I turned the extensions off just to see if it made any difference. There is an interaction with null move as you predict If I turn null move off, I find the draw in about 30 seconds. Again as you say, Kd2 (presumably followed by fail high null move with insufficient depth left to see the draw) seems to be the 'problem'. After playing down to Kd2 I find the draw in seconds. Frank
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