Re: [Bug-gnubg] Bug: 14 point one-sided race databasewithmakebearoff.exe

[Joern Thyssen]

On Sun, Jan 09, 2005 at 01:36:02PM -0800, Ned Cross wrote
> As I recall, the race net is very good, and the 13 point should cover 
> most common non-contact scenarios, so I would be willing to guess the 13 
> point database is the limit of diminishing returns for most users anyway.
> 
> Is there a scenario where having the database to the 14 point or beyond 
> is truly a performance improvement?

Actually the performance is worse using the databases as the I/O takes
more time than a neural net evaluation.

Joseph did some comparisons between the 12pt bearoff database and the
neural net. For example, 2-ply had an avg error rate of 0.0000209 and
made ~4% chequerplay errors for a set of 34000+ positions.

For 0-ply the percentage of chequerplay errors increases with the
"range", e.g., only 4% errors for positions where the outermost chequer
is on the 7pt compared to 9.5% for the 12pt. This suggests that the
database could be needed for even "longer" races. However, 2-ply lowers
the error rate and I think you'll rarely see interesting races where one
side has multiple chequers further out than the 13pt (unless he is
strugling to save a gammon). 

J?rn

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