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Subject: Re: What is the q-search?

Author: Antonio Dieguez

Date: 20:52:48 01/09/00

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On January 08, 2000 at 15:39:05, Tom Kerrigan wrote:

>On January 08, 2000 at 12:41:13, Antonio Dieguez wrote:
>
>>On January 08, 2000 at 11:56:25, Dan Andersson wrote:
>>
>>>>"Extensions" are usually used to keep a program from running out of search
>>>>depth. My understanding was (probably very wrong) that extension are some kind
>>>>of addition search done for few next plys deep. If this is really so, how can
>>>>extension "keep program from running out of search depth"?
>>
>>that phrase traduced to spanish is not very clear I suppose you have the same
>>little problem, may be keep program from running out means keep program running
>>in ?
>>
>>>You said it yourself! By adding more depth.
>>>
>>>Regards DAn
>
>To jump the gun on Bruce a bit... If you are using some sort of recursive
>alpha-beta function, one of the arguments to that function is "depth". If you
>want to do a 10 ply search, you call the search function with depth = 10. For
>each successive call to search, depth is tyically decreased by 1. When it
>finally hits 0, it has "run out of search depth," so the quiescence search is
>called.
>
>An extension will increase the depth at a particular node. Let's say depth = 5
>and you've reached a position where the side to move is in check. Typically,
>depth is increased to 6, so the position is searched 1 ply more than it would
>normally be. This is good because checks indicate that something is going on
>tactically in the position and you want extra accuracy when evaluating it.
>
>-Tom

very clear, thanks for your time and response Tom.I just ever called to te
qsearch a extension too... but the language division is good.

btw, suposing that if you do a nullmove and if you get mated you do a 1 ply of
extension , have happened to you that sometimes a continuation never get
finished? had happened to me various times especially if the mate is with a move
catalogued as a losing capture... btw too, has been said that killer captures
have not worked good, but losing captures that causes a cut off should be
considered as a killer capture? doesnt look bad.

-Antonio



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