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Subject: Re: What is the branching factor for this position?

Author: Tom Kerrigan

Date: 15:17:12 08/10/00

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On August 10, 2000 at 17:42:24, leonid wrote:

>On August 10, 2000 at 16:51:08, Tom Kerrigan wrote:
>
>>On August 10, 2000 at 15:45:06, leonid wrote:
>>
>>>On August 10, 2000 at 13:58:22, Tom Kerrigan wrote:
>>>
>>>>On August 10, 2000 at 07:54:32, leonid wrote:
>>>>
>>>>>On August 09, 2000 at 21:44:38, Tom Kerrigan wrote:
>>>>>
>>>>>>On August 09, 2000 at 17:32:48, leonid wrote:
>>>>>>
>>>>>>>On August 09, 2000 at 17:04:37, Tom Kerrigan wrote:
>>>>>>>
>>>>>>>>On August 09, 2000 at 15:59:24, leonid wrote:
>>>>>>>>
>>>>>>>>>>I don't recall Ed ever calling his search brute force.
>>>>>>>>>>
>>>>>>>>>>-Tom
>>>>>>>>>
>>>>>>>>>If it is so, now I see why my branching factor is so miserable.
>>>>>>>>>
>>>>>>>>>I asked above question when I tried to solve this position by brute force. For
>>>>>>>>>black side I looked up to 10 plys deep and it took already 12 min 17 sec. Move
>>>>>>>>>was wrong.  Black knight goes to the position e2. And for finding right move I
>>>>>>>>>must go to the next 12 plys search. But this could take some next 6 hours. This
>>>>>>>>>is how my old question about branching factor came to me. It prohibit to my
>>>>>>>>>program to see very rapidly and reach far distance.
>>>>>>>>
>>>>>>>>You're the only person in the entire world who does these "brute force"
>>>>>>>>searches.
>>>>>>>>
>>>>>>>>-Tom
>>>>>>>
>>>>>>>When you want to know if your basic speed is the right one, only brute force
>>>>>>>search could say you so. This I remember from writing my program for finding
>>>>>>
>>>>>>I don't know what basic speed means, but I'm sure that there isn't a right one.
>>>>>>And a fixed-depth brute force search with no extensions and no quiescence search
>>>>>>won't tell you anything useful.
>>>>>>
>>>>>>-Tom
>>>>>
>>>>>Tom, if you compare two programs that do its search, but not by brute force, you
>>>>>actually compare "pruning technics" for both of them. But how much program with
>>>>>good pruning technics still miss from its potential, you will find by seeing its
>>>>>brute force speed only.
>>>>
>>>>What potential? Presumably the pruning techniques are increasing the program's
>>>>potential, otherwise the author wouldn't use them.
>>>>
>>>>-Tom
>>>
>>>The same pruning technics, in two programs that have different brute force base,
>>>winner will be program with best brute force speed. But by the same talken, it
>>>could be said that program with best pruning technincs could be speeded even
>>>more by speeding its brute force part. Sometime this brute force speeding will
>>>simply forgotten when program already shine with its advanced pruning
>>>capability.
>>
>>The speed of a forward-pruning program can be tested (and improved) just as
>>easily as any other program.
>>
>>My point is that your "brute force" searches are extremely stupid and there's no
>>reason for anyone to do them ever.
>>
>>-Tom
>
>Everybody can choose its own way. In the first part of my program I did exectly
>like you said, pruning technics first and brute force second. My second part I
>go opposit way. Experience say me that this way is logical. For you entire game
>start and end with one part. Here we are different.

I made a copy of my program that does your brute force searches, i.e., no check
extension, no quiescence search, and no null move. I called it "Stupid."

I played a match between Stupid and my program.

Stupid lost 20 games in a row. It usually got mated around move 30. Once in a
while it would last for 50-60 moves.

So basically, you can add 3 things that are well-understood and that everybody
has and you can immediately increase your program's strength by 400+ points, or
you can continue down your brute force path and never have a strong program.

-Tom



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