[computer-go] 10k UCT bots

[Álvaro Begué]

On Tue, May 13, 2008 at 2:28 PM, Mark Boon <tesujisoftware at gmail.com> 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 care much about it being noticeable. This thread is about
putting bots on CGOS that use a reproducible algorithm, to help people
detect bugs in their implementations. As part of specifying what these
bots do, we should all pick the next move in a playout using the same
criteria. If we agree to use uniform distribution among empty
non-eyeish points, that's what should be implemented.

> 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 don't think you understood the algorithm. The eyeish point is
removed from the lottery only for picking this particular move, not
for the rest of the playout.

> 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.

Reproducibility was the point, not strength of the bot.

> If this asymmetry really bothers you, you could very easily fix this by
> wrapping the search around. There's no asymmetry in a circle.

That doesn't fix anything.


Álvaro.