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Subject: Re: Wu/Beal predates Koistinen

Author: Tony Werten

Date: 07:27:07 12/04/01

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On December 04, 2001 at 10:01:23, guy haworth wrote:

>
>Thank you:  I was not familiar with the publication of Urban Koistinen and have
>followed your pointer to it.
>
>It is clear that the EGT-generation method of Wu/Beal predates the April 2001
>publication by UK.  It seems that the WB-approach has been in the pipeline since
>work at QMWC (London) started about 1994.
>
>It has been published in the International Systems Journal (2000) and in the
>ICGA_J_v24.3 (Sept 2001).
>
>
>For the record, you should note that the Wu/Beal method has two minor flaws,
>easily spotted when used:
>
>a)  accidentally omits to inherit subgame-wins-in 0 and 1 in DTC-mode
>       ... although this was clearly intended
>
>b)  does not ensure that there are at least as many cycles as the max depth of a
>subgame win.  [ It is theoretically possible for the last cycle to have
>discovered nothing new but there still to be subgame wins to inherit. ]
>
>Also, I suspect the Wu/Beal method does not make full use of bitmaps, minimising
>the use of the depth-databases as much as possible (as per Ken Thompson, 1986).
>John Tamplin proposes bitmaps for 'residual unknowns' as well as 'positions
>resolved so far'.  Anything that improves efficiency at 6-man level is good
>news.
>
>So there are improvements to be made, even now.

I think so to, but I have to admit that I don't understand Urbans paper
completely. Now with Wu-Beals paper I understand more of it and I am wondering
if he made the improvements Wu and Beal didn't.

The WB paper just seems to touch a good idea without really seeing the
possibilities.

Tony

>
>G



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