Author: Uri Blass
Date: 11:30:07 04/19/05
Go up one level in this thread
On April 19, 2005 at 13:16:41, Uri Blass wrote: >On April 19, 2005 at 07:38:56, Uri Blass wrote: > >>On April 19, 2005 at 07:28:01, Uri Blass wrote: >> >>>On April 19, 2005 at 05:21:30, Ross Boyd wrote: >>> >>>>On April 18, 2005 at 22:55:31, Uri Blass wrote: >>>> >>>>>On April 18, 2005 at 22:41:37, Uri Blass wrote: >>>>> >>>>>>On April 18, 2005 at 22:29:09, Uri Blass wrote: >>>>>> >>>>>>>On April 18, 2005 at 21:32:59, Jeremiah Penery wrote: >>>>>>> >>>>>>>>On April 18, 2005 at 07:24:11, Uri Blass wrote: >>>>>>>> >>>>>>>>>part of the problem is check extensions and part of the problem is probably >>>>>>>>>pruning based on evaluation together with other factors that I should improve. >>>>>>>> >>>>>>>>Why should check extensions make any difference in this position? Neither side >>>>>>>>should be giving any checks. >>>>>>> >>>>>>>The problem is that most of the search time is not on the right line but in what >>>>>>>happens after queen promotion. >>>>>>> >>>>>>>Movei cannot find the knight promotion in a reasonable time(I did not try more >>>>>>>than 30 minutes on a fast PC) but almost all the search time is on queen >>>>>>>promotion. >>>>>>> >>>>>>>After performing the knight promotion finding the mate is easy for movei. >>>>>>> >>>>>>>Uri >>>>>> >>>>>>Note that check extensions was only a thought and I am not sure that it is the >>>>>>problem. >>>>>> >>>>>>single reply extensions after queen promotion may be a bigger problem(single >>>>>>reply extensions are done also after a knight promotion but they do not help >>>>>>much because depth reductions that is not null move pruning are also used and >>>>>>probably they are used more after knight promotion). >>>>>> >>>>>>Uri >>>>> >>>>>Checking show that you are right that check extensions are not the problem and >>>>>single reply extension is the problem that prevent movei to go deep because >>>>>after queen promotion there are a lot of moves that force single reply that are >>>>>not checks. >>>>> >>>>>Uri >>>> >>>>:-) >>>> >>>>That sounds like the cause of the problem. The tree would explode. Do you limit >>>>single replies in any way? In 99% of positions its not going to be a problem >>>>anyway, so no need to fix it. Maybe put a hard limit of 4 non-check extensions >>>>or whatever works best. >>>> >>>>Ross >>> >>>I limit them but the limit is not based on their number but based on evaluation >>>and if the side that force the single reply is clearly winning I do not extend. >>> >>>Uri >> >>I hope that I have another idea to limit them and also to limit check extensions >>but I am not sure if it works and I plan to try it. >> >>I know that there are positions that movei cannot go deep because of heavy check >>extensions(this position is not the case) and I have an idea how to stop it. >> >>Uri > >Latest private Movei after limiting extensions can solve the position at depth >22 after less than 25 minutes and 952561647 nodes on fast hardware. > >failing high happen after 528430410 nodes. > >I will check if limiting the extensions also work in test suites. > >Uri After fixing a bug that caused it not to extend the first move it is only 952557602 nodes at depth 21 and 528426365 nodes to fail high. Note that Movei does not use hash for pruning and I believe that using hash for pruning is more important in that type of positions for programs that solve it. Uri
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