Author: Robert Hyatt
Date: 20:13:26 07/21/04
Go up one level in this thread
On July 21, 2004 at 23:03:59, Eric Oldre wrote: >On July 21, 2004 at 22:09:58, Robert Hyatt wrote: > >>On July 21, 2004 at 16:55:07, Eric Oldre wrote: >> >>>lets say you are searching a position with iterative deepening. >>>at depths 3,4,5 it finds a best move of Qd3. then at depth 6 >>>the best move changes to c4. >>> >>>When you start searching to depth 7, you clearly would want the >>>first move you search to be c4, and this shouldn't be a problem >>>if your transposition tables are working right. Since the best >>>move should be stored in it. >>> >>>however, a good move to try 2nd would be Qd3, but your transposition >>>tables aren't going to let you know that, at least not in the implementations >>>that I have normally heard about. >>> >>>I was thinking that one way to overcome this would be to keep 2 "best" moves >>>in the trans table. one to try first, and one that was a best move, before >>>being replaced by a deeper search. >>> >>>Are other people doing this? or have you discovered that the cost is greater >>>than the benefit? >>> >>>Eric >> >> >>Nobody uses the transposition table to order the moves at ply=1. > >Well not quite, I do! You only have _one_ position at the root of the search. How many moves can you store in one position? :) More than one is a huge waste since "best" is all that counts in alpha/beta... > >Of course i hope to get that replaced in the future with something better. :) > > >> Much easier is >>to just generate the ply=1 move list before you start the search, and as you >>find a new best move, move it to the top of the list, pushing others down 1 >>slot. This makes you search the best move from the previous iteration first, >>then the next-best move from the previous iteration second, etc...
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