Mark Boon wrote:
On 13-mei-08, at 15:08, Jason House wrote:
The range of the random number is reduced by one after each failed
lookup. Shuffled data has no impact on future use of the array of
empty points.
OK, I understand now why a point at the end (or beginning) is a little
less likely to be picked. Although I still have doubts whether that
will lead to a noticable bias, I'll try to think about it.
I don't believe there is any bias based on where a good point is, only
where the bad points are. Because you can think of this list of empty
points as a circular array, where no particular location is any more
significant than any other.
I would imagine moving an illegal point towards the end and only start
including it when the other 'legal' moves run out can lead to terrible
bias however because they may not remain illegal for very long and
actually become important points to play. A ko-point is probably the
most extreme example of that.
I had a "bug" in my program that may have been an actual improvement.
I did not always resurrect empty points that were eyes. I went ahead
and fixed this and didn't try to assess whether it was a "good bug" or
not but I didn't notice any improvement. The net effect was that if a
move was an eye move that you shouldn't move to, and the opponent
moved to a diagonal, the program still would not move to it. That's
probably sound in some cases and not in others.
Anyway, I don't bother to order the empty-point-list or scramble them
in any way prior to the game. So the first point is the 1-1 point and
the last is the 19-19 point (or whatever boardsize you're playing) so
I have no qualms about those moves being a little less likely to be
played. Or even a lot less. I think it would actually be beneficial.
If this asymmetry really bothers you, you could very easily fix this
by wrapping the search around. There's no asymmetry in a circle.
Mark
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