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Subject: Re: A move to search 2nd... Keep in the trans table?

Author: Eric Oldre

Date: 21:16:36 07/21/04

Go up one level in this thread


On July 21, 2004 at 23:13:26, Robert Hyatt wrote:

>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...


i think that you might have misunderstood what i was trying to say, or i
misunderstood you...

I meant i get the first move to search from the trans table. and then use SEE
after that.








>>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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