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Subject: Re: How to manage search depth in limited time?

Author: Robert Hyatt

Date: 12:16:57 03/16/01

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On March 16, 2001 at 11:04:01, Miguel A. Ballicora wrote:

>On March 16, 2001 at 08:51:52, Robert Hyatt wrote:
>
>>On March 16, 2001 at 00:23:21, Pham Minh Tri wrote:
>>
>>>Hi,
>>>
>>>Suppose the time for searching a move is limited in T minus. And a program has
>>>just finished the iterative loop of depth N. My question: How to decide that the
>>>time left is enough for the next loop (depth N+1) or not?
>>>
>>>(Some books suggested me to continue searching next depth and interrupt when
>>>time is over. But I don't like this method because of wasting time.)
>>>
>>>Any suggestions would be very appreciated.
>>>Pham
>>
>>
>>Just start the next iteration period. If you don't have time to get a move
>>back, you still have time to fail low, which can signal you to use more time
>>to find a better move.  When you run out of time and make the move, the
>>"ponder search" will pick up where you stopped due to everything being saved
>>in the hash table...
>
>This is an idea that I haven't had time to try (of course, most probably it
>was tried before by somebody else...).
>Suppose this scenario: I have alloted 30 s for the move, I finish one iteration
>at 20 s so most probably I won't be able to finish the next one on time.
>Would it be useful to go to the next iteration searching with alpha, alpha+1
>just to test if the pv_move fails low? If it doesn't, I just return that move.
>
>Regards,
>Miguel


I just search with the normal aspiration window. Fail lows are 30 times easier
to compute than normal or fail high moves.  Because one move at ply 2 is enough
to cause the root to fail low.



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