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Subject: Re: Forward Pruning...

Author: Joshua Haglund

Date: 14:20:33 02/29/04

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On February 29, 2004 at 16:33:46, Uri Blass wrote:

>On February 29, 2004 at 16:29:15, Joshua Haglund wrote:
>
>>On February 29, 2004 at 12:48:06, Uri Blass wrote:
>>
>>>On February 29, 2004 at 12:20:03, Joshua Haglund wrote:
>>>
>>>>On February 29, 2004 at 03:20:30, Matthias Gemuh wrote:
>>>>
>>>>>
>>>>>
>>>>>
>>>>>My engine has a very unstable and unreliable search.
>>>>>Sometimes I think I implemented what you are proposing.
>>>>>My opinion is that the blindness introduced by such tricks would really hurt.
>>>>>
>>>>>/Matthias.
>>>>
>>>>yes! it wouldn't do the best search if it didn't reach great depth where f = 3;
>>>>If your engine searches deep try ply > 12. If it doesn't try ply 8, etc... :)
>>>>
>>>>
>>>>I have reason to believe a person will gain atleast 1 ply in the same amount of
>>>>searched time.
>>>>
>>>>example
>>>>time = 30;
>>>>ply 7 = 4 seconds.
>>>>ply 8 = 13
>>>>no more plies reached.
>>>>
>>>>// with idea.
>>>>time = 30;
>>>>ply 7 = 1 second
>>>>ply 8 = 5
>>>>ply 9 = 20 seconds
>>>>
>>>>Maybe this would be good for long time controls? Skip shallow and go to deeper
>>>>lines.
>>>>
>>>>Thanks for your reply,
>>>>
>>>>Joshua Haglund
>>>
>>>I can only say that I do not understand your idea.
>>>
>>>If you suggest to do selective search in the first plies then it seems to me a
>>>bad idea because you may miss important moves.
>>>
>>>It is more logical to be selective in the last plies and programs do it for
>>>example by qsearch but even then I do not see why do you use fixed number of
>>>moves and the number of moves that you search should be dependent on the
>>>position.
>>>
>>>prunning illogical moves is something important to do and programmers know it
>>>so it is not new information.
>>>
>>>Uri
>>
>>I thought about doing a selective search also... pretty much the same thing.
>>
>>If you skip time wasted looking at first several plies, it'll get to a greater
>>depth in less time to look for good moves.
>>
>>Thanks for your reply,
>>
>>Joshua Haglund
>
>selective search is good only in the last plies when the remaining depth is
>small.
>

Here I do not follow you. What you are saying is you can only search so deep.
The only thing I consider last ply is the last ply searched. If we get to depth
90 i'm sure that isn't the last ply, unless mate occurs.



>In this case you can relatively safely prune sacrifices because even if they are
>correct you usually do not have enough depth to see it.
>
>Uri

This idea has nothing to do with specifically pruning sacrifices, but just
cutting the number of moves to look at so we get deep quicker, so we can start
looking for better lines at greater depth and start looking at all moves
possilbe instead of 3; not waisting time at shallow depth.

Thanks for you replies,

Joshua Haglund



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