Author: Uri Blass
Date: 12:47:02 02/10/01
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On February 10, 2001 at 14:40:37, leonid wrote: >On February 10, 2001 at 13:27:32, Uri Blass wrote: > >>On February 10, 2001 at 12:43:05, leonid wrote: >> >>>On February 10, 2001 at 12:00:30, Uri Blass wrote: >>> >>>>On February 10, 2001 at 11:08:17, leonid wrote: >>>><snipped? >>>>>What is the "ss=10" ? >>>> >>>>ss is the selectivity search parameter of chessmaster. >>>> >>>>I know from experience that chessmaster is usually faster in solving problems if >>>>I give it bigger selectivity. >>>> >>>>The default value is 6 and the maximal value is 10. >>> >>>Probably it is the maximum number of moves to see in each ply. When mine solved >>>this position this variable was at 6. >>> >>>Leonid. >> >>It is not. >> >>I believe that it is about null move pruning. > >If it is really so, my guess is completely wrong. I even feel me sure that null >move in mate solutions is the wrong way to proceed. It should lead to mistakes. It can cause problem in endgames when a zunzwang is possible but I do not think that it can cause problems in positions with a lot of pieces in the board. Most of the moves in the solutions are checks so searching quiet moves to reduced depth can help. I guess that Chessmaster has also mate extensions and it means that it checks if there is a mate threat to relatively bigger depth before deciding to prune by null move pruning. > > >>Chessmaster shows two depthes. >>The first number is usually small(1 in the first iterations). >>The second number is bigger when the difference between them is not more than >>the selectivity. > >I am lost. I will give a simple example if selectivity=6 then depth 1/6 and 1/7 is possible because the difference is not bigger than 6 but depth 1/8 is impossible. > >>I guess that Chessmaster does not use the null move pruning in the first plies >>but it is using null move pruning everywhere in the tree later. > >As I said before, after the description of the null move that I have read here, >null move should lead to mistakes. Since Chess Master is very good in solutions >of mates, I presume that he do something different. It could be that somebody >could indicate what it really is. > >>I believe that when chessmaster shows depth 1/4 it means that it looks at >>everything at depth 1 in the tree. > >>It also looks at everything at depth 4 except move that it prunes because of >>null move pruning and it also does a lot of extensions so it can practically see >>mate in 10 at depth 1/4. >> >>I know from experience that chessmaster waste a lot of time on stupid lines if I >>give it a low selectivity because it does not prune lines with no threat. > >Problem with all those stupid moves is that sometime they are the best one. When I say stupid moves I do not mean to sacrifices but to move that threat nothing. Uri
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