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Subject: Re: Combining Internal Iterative Deepening, History and Killers

Author: Tony Werten

Date: 00:41:47 07/07/01

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On July 06, 2001 at 23:08:07, Robert Hyatt wrote:

>On July 06, 2001 at 14:27:39, Artem Pyatakov wrote:
>
>>I was taking a peek at Crafty's source code and came across this comment inside
>>the Search() function:
>>----------------------------------------------------------
>>|                                                          |
>>|   if there is no best move from the hash table, and this |
>>|   is a PV node, then we need a good move to search       |
>>|   first.  while killers and history moves are good, they |
>>|   are not "good enough".  the simplest action is to try  |
>>|   a shallow search (depth-2) to get a move.  note that   |
>>|   when we call Search() with depth-2, it, too, will      |
>>|   not have a hash move, and will therefore recursively   |
>>|   continue this process, hence the name "internal        |
>>|   iterative deepening."                                  |
>>|                                                          |
>> ----------------------------------------------------------
>>
>>The comment makes complete sense and "Internal Iterative Deepening" sounds like
>>a great idea, but could somebody  please explain to me how to integrate this
>>algorithm with the Killer and/or History heuristics? Thanks in advance.
>
>
>Simple.  If this is a PV node, use IID.  If it is not a PV node, then use
>the normal history/killer stuff as that is good enough.  But on the PV, you
>are searching one ply deeper, and the history/killer stuff is not as accurate.

Hi Bob,

from testing I found out it saves a little less than 2%. Should it be more or is
it ones of these things that don't hurt except in a couple of positions where
not having it would kill you ?

cheers,

Tony




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