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Subject: Wu/Beal predates Koistinen

Author: guy haworth

Date: 07:01:23 12/04/01

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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

So there are improvements to be made, even now.


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