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

[Rémi Coulom]

Darren Cook wrote:
>> I've been messing around with where to apply heuristics. Candidates
>> include:
>>
>> 1) In the UCT tree, since this is earliest in each playout.
>> 2) In the moves beyond the tree ("heavy playouts"), since this is where
>> most of the moves happen. Because this part is so speed-critical, ...
> 
> Remi (using learned patterns instead of heuristics, but should be the
> same) got dramatic improvements doing both (see quote below).
> 
> It is also my understanding that in Crazy Stone the patterns are being
> used at every ply in the playouts; given that the program is being given
> a constant time it seems the overhead of this is more than made up for
> by the increase in strength.
> 
> Darren

Interestingly, I got no overhead when I added 3x3 patterns. It even made 
simulations faster, because detecting illegal moves or moves into eyes 
came for free.

Rémi