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Subject: Re: Aborting a search

Author: Robert Hyatt

Date: 06:59:00 03/18/03

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On March 18, 2003 at 04:18:05, Ed Schröder wrote:

>On March 17, 2003 at 21:54:36, Nathan Thom wrote:
>
>>Im having troubles trying to figure out what to do with my search results when a
>>timeout occurs. eg I could have searched 10 plies fully, and am part way through
>>the 11th ply when time runs out.
>>
>>The simplest thing to do is ditch all results from the last incomplete search
>>and just go with what you had after 10 plies. But this seems a big waste.
>>
>>Thoughts?
>
>Nathan,
>
>It's quite simple, just check the "time_is_up" condition after your "undo_move"
>call and jump to the place where you climb back one ply in the tree (as if there
>are no more moves to search on the current ply).
>
>My best,
>
>Ed


This can be a fatal error.  You are at ply=N and have 10 legal moves to search.
The first is horrible, but the second wins everything.  If you quit after
searching the first move and return that score, the previous ply may well like
the move it tried, and since it has now searched every move, it backs the
score up.  And so forth.  But when the game really enters this path, the
first move is not actually played by your opponent, he plays the second, and
the roof falls in.

You have to _not_ back up things from below the root, once you have decided that
time is up.



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