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Subject: Re: Is the Depth directly proportional to the program's strength? (YES!)

Author: Sune Fischer

Date: 07:37:19 02/06/02

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On February 06, 2002 at 10:19:29, William H Rogers wrote:

>So it would seem, but the search is exponential and not linear.
>I think you should not consider the "depth" but rather the number of nodes
>searched.
>If you go one ply deeper then (assuming your branch factor (BF) is not too depth
>dependent) you a factor of BF more nodes, this ratio is fairly constant so I'd
>go with Uri's definition.
>
>The diminishing returns issue is probably an effect of converging towards the
>ideal move as often as possible.
>
>-S.
>
>I vote for your analisis. Just for an example lets say that a program can only
>search to a level of 10 plys and it thinks that it has found its very best move,
>then lets assume that we can search 2 to 4 plys deeper and it discovers that
>there is a better move that can help it win the game. This happens all of the
>time in chess and in other zero-sum games. The deeper you search the better you
>game will be, of course it really depends on your evaluation routine is
>basically sound in the first place.
>Bill

I agree, if we forget about chess programs and just study chess, then we can
ask:

A:) What is the percentage of ideal moves that can be found at ply 0 ?
B:) What is the percentage of ideal moves that can be found at ply 1 ?
C:) What is the percentage of ideal moves that can be found at ply 2 ?
D:) What is the percentage of ideal moves that can be found at ply 3 ?
E:) What is the percentage of ideal moves that can be found at ply 4 ?
etc...

Now obviously this percentage cannot be constant since it must sum to 1, so it
has to be descending which means diminshing returns.
Exactly what type of function that is I do not know, but it would interesseting
to find out :)

-S.



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