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

Author: Larry Griffiths

Date: 10:54:10 08/11/00

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On August 11, 2000 at 05:57:22, leonid wrote:

>On August 11, 2000 at 00:02:39, Larry Griffiths wrote:
>
>>Leonid,
>>
>>I am wondering now if I am confusing BruteForce with Minmax.  I always thought
>>BruteForce was generating ALL the moves (or another name for MinMax).
>
>It could be that I am confused with name. It happen to me often. Never mind.
>Will just say what I see as Brute Force. Brute Force look all the possibility in
>given position before it reach its decision. It is not forced to see all the
>moves in each ply for doing so. In MiniMax you see all moves (nodes) for each
>ply before saying your result.
>
>
>>Anyway, I ran your position to 6 plys and here are the results...
>
>Some data still is useful for me even if I am doubious about my Brute Force
>branching factor.
>
>>
>>TCBoard - RunMinMax()
>>
>>Elapsed Time= 1125.38 seconds
>>
>>Ply ---CAPTURES-- -----MOVES----- -----TOTAL----- ---Invalid---
>>  1             5              30              35             2
>>  2           130           1,065           1,195            93
>>  3         6,613          35,468          42,081         2,107
>>  4       199,119       1,282,187       1,481,306       107,805
>>  5     8,725,158      43,530,271      52,255,429     2,555,427
>>  6   281,688,872   1,585,505,759   1,867,194,631   132,999,965
>>    _____________ _______________ _______________ _____________
>>      290,619,897   1,630,354,780   1,920,974,677   135,665,399
>>
>>        Captures/Moves Per Second=      1,706,964
>
>
>What is interesting for me in your table is the "INVALID" number. Probably you
>generate invalid move in move generator and only lately you see if it is legal.
>

This is indeed true.  The postings here lean toward making move generation lean
and mean and doing checking on the back end in hopes the alpha-beta cutoffs will
eliminate the extra cpu overhead in validating moves.

>
>Must I understand Capture/Moves as simply "illegal moves generated by second"?
>And is this number 1 707 964? And on what computer?
>

Captures/Moves is "LEGAL" moves/unmoves made per second. It is Total legal
captures + Total legal moves / Elapsed time.  The invalid moves made/unmade are
not included.  I ran this on a Pentium III Xeon 550Mhz machine.

>
>>The branching factor looks like it is between 35 and 36 using MinMax.
>>This is what I have found to be documented for the average number of moves
>>for a side.
>
>For this I have special fonction in my program. It do usual search by Brute
>Force but only generate for each ply all its legal moves. This permit constant
>saying of average moves for given position. Have this for 8 and 10 plys deep
>search.
>
>Thanks for response,
>Leonid.
>
>>Larry.



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