Computer Chess Club Archives




Subject: Re: Deep Search Extension

Author: Heiko Mikala

Date: 15:52:44 01/21/98

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On January 19, 1998 at 04:21:26, Ernst A. Heinz wrote:

>On January 18, 1998 at 18:53:15, Bruce Moreland wrote:
>>On January 18, 1998 at 10:37:59, Robert Hyatt wrote:
>>>(...) The idea was to shift the null-move window downward, and
>>>then notice whether the null-move search fails high or low.  If it fails low,
>>>(...) you extend by 1 ply.
>>The only place I've read about this recently is on the Dark Thought
>>page.  Are you guys still doing this, or am I confused?
>Yes, I have modified and fine-tuned the original deep-search rules quite
>a bit in order to make the extension usable. I still like it (...)

Could you or Bob or someone else maybe try to explain this extension
in a bit more detail? I don't understand what is meant by "shift the
move window downward". Also, someone wrote, that this extension
should only be used near the leaves of the tree? Is it possible to use a
zero-width window for the null-move in conjunction with the deep search
extension and does one extend on all fail-lows?

I tried Bruce's mate threat extension (everyone did, I guess...), and it
works fine.

After that I tried the deep search extension in the way I understood it,
but the only effect was an exploding search tree, so I guess I'm missing
an important point...

Thank you very much, and, wow, this is a fantastic newsgroup!
It is very impressive and very very interesting to listen to all you
out there!
I've been working on my own chess-program for some years, read
some books and many articles about chess programming, but this
group motivated me to start again (or go on) to work on my old

Thank you all,


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