Author: Harald Lüßen
Date: 05:48:48 09/25/04
Go up one level in this thread
On September 25, 2004 at 07:19:21, Andrew Platt wrote: >On September 25, 2004 at 06:35:57, martin fierz wrote: > >>4) i never thought much about verified 0-move pruning. but a post i read last >>week made me think: i always thought i could do the following: >> >>if(pieces > 0) >> if nullmove-fails-high >> return value; >>if(pieces == 0) // do a verification search >> if nullmove-fails-high >> verify result with a normal search with reduced depth. >> if verification-search-fails-high >> return value; > >The standard verification search doesn't have your condition above. It just says >if it fails high, verify. > >>now there was this post saying that this won't work because you have to disable >>the nullmove in your entire verification search. i don't understand why that >>would be? can somebody explain? > >I don't know if this was from the posts I was making about problems I was having >but that's not exactly the solution you want. The key point is that even when >verifying a null move search you are still doing null moves lower down the tree >and they could be causing problems too. However, you won't verify those becuase >you are in verify mode. So now you are doing an R=3 null move and could miss >some things. What mode? Are the nullmove algorithms in deeper plies dependent on a decision of a shallow ply? I thought they are independent with the exception of avoiding double nullmoves. A possible deep ply nullmove is done when there are pieces and verified when it fails high. And when a search with a small depths with or without nullmove backs up its score I could trust it whether I am in a normal search or in a verification search. That is the trick with recursion. Where am I wrong? Is it explained in the original verification search document? Harald
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