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Subject: Re: Hashkey collisions (typical numbers)

Author: Robert Hyatt

Date: 11:16:31 04/07/04

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On April 07, 2004 at 11:27:47, Vincent Diepeveen wrote:

>On April 07, 2004 at 11:04:23, Robert Hyatt wrote:
>
>>On April 07, 2004 at 10:54:40, Tony Werten wrote:
>>
>>>On April 07, 2004 at 10:48:23, Renze Steenhuisen wrote:
>>>
>>>>
>>>>>>>>>I'm sure it was some implementation bug with Renze.
>>>>
>>>>Anyone,
>>>>
>>>>I only store result from the main search, so no NULL-move and no Qsearch
>>>>results.
>>>>I get a TT-hit ratio of 11.73%, of which a part will generate cut-offs.
>>>>    (I call something a tt-hit when an entry is found with the same hashkey,
>>>>     draft does not need to be sufficient)
>>>
>>>Hmm, I'm sorry but that's way too low. You probably have a problem with your
>>>hashkey.
>>>
>>>In XiniX I get a hitrate of at least 60% in normal search, >20% in qsearch.
>>
>>That can't be right unless you are talking positions like Fine 70...
>>
>>Too many have run that experiment over the years and 30% is the _highest_ number
>>I have ever seen reported in opening/middlegame positions.
>
>Xinix is a very efficient searching program with a good qsearch.
>
>Better qsearch means more efficient main search.

Has absolutely _nothing_ to do with number of "transpositions" however...

That is simply a characteristic of the tree being searched and its size and
number of branches...

If you get over 30% hash hits, something odd is going on in the middle game.  IE
horrible move ordering or something...


>
>
>>
>>>
>>>Tony
>>>
>>>>
>>>>the tt_retrieve code retrieves a move, which I call the TT_MOVE_SUGGESTION.
>>>>
>>>>could someone provide me with a % of TT_MOVE_SUGGESTIONs in a search?
>>>>
>>>>Cheers...



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