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Subject: Re: Forward Pruning...

Author: Joshua Haglund

Date: 20:39:02 03/01/04

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On March 01, 2004 at 14:14:33, David Mitchell 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
>
>Joshua, your idea is a great way to get deep, and very fast.
>
>Unfortunately, the well you are digging will not have any water in it, no matter
>how deep, or how fast, you dig down. :)
>
>You can't throw out several shallow moves, and go onto the deeper parts
>remaining, and have success with Alpha beta. Every shallow move you throw away
>has it's _own_ deeper moves, which may lead to the best positions available.
>
>You will _never_ recover from that loss by simply going deeper with the
>remaining moves into the search tree.
>
>In a game like Tic-Tac-Toe, you can do that, sometimes. In chess, you can't
>recover. Try it and you'll see for yourself.
>
>dave

Hi Dave,

I haven't had much success than a couple of "wins". On the other hand I do have
success with searching deeper a ply or two.

Thank you for your reply,

Joshua Haglund



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