[computer-go] Efficiently selecting a point to play in a random playout

[Łukasz Lew]

Hi,

I've tested many approaches, and the one I implemented is clearly the best.
The bias that Peter Drake talks about is negligible and doesn't have a
noticeable impact
on playout results.
(and uniformity of playout isn't something to fight for in MC Go)

Jason, can You tell me why You don't want to use libego instead?
Actually this is open question to all comp-go readers.

Is libego too complicated? Do You have problems with compilation?
Or You are not comfortable with the GNU license? Any other reason?

Best Regards,
Lukasz Lew


On 5/27/07, Jason House <jason.james.house at gmail.com> wrote:
>   As I get into the home stretch of rewriting the core of my bot, I want
> to add a monte carlo player.  I've realized that picking a random move
> to play is non-trivial since it's such a key element in playout speed.
>
>   An array of legal positions has easy lookup, but may not be easy to
> maintain... I guess it'd require storing a mapping between board
> position and index into the legal positions array so that a move that
> becomes illegal can be quickly removed (by moving the item from the tail
> of the array into the empty location).
>
>   Looking at libego, I see it does a variant on this where it maintains
> an array of empty points.  If the random index it picks is disallowed,
> it'll scan through the array (with wrapping around the end) until it
> either finds an allowed move or returns to its starting point.
>
>   Which methods have people tried and what works best?
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