[Computer-go] "Power of Forgetting" paper

[Martin Mueller]

> What I perceive is that Orego, while "Mogo-like," still has a fairly light
> playout policy. For example, in the paper, Orego (using the
> killer-reply-with-forgetting heuristic) defeats Gnugo maybe 87% at 32K
> trials on 9x9, whereas Pebbles defeats GnuGo 93% using 10K trials.
> 
> Orego places the killer-reply heuristic as the very first rule applied. I
> speculate that engines that employ heavier playouts will benefit from
> placing a killer heuristic farther down the rule set.

Yes, this is pretty close to what we found with Fuego.
The method in the old paper (without forgetting) did not work for us at all.
The new method with forgetting works, but only on big boards and only as a later rule. I think we used it as the last rule before random. I forget the details, but it was something like 62% wins in selfplay on 19x19 in relatively fast games. Arpad did the tests, maybe he can reply if he reads this.

This is not yet in the Fuego codebase - it needs more testing to see if it works on 13x13 and how it behaves in tournament-like (more time, multicore) conditions.

I have become more cautious about modifying the policy because often ideas that are good with few simulations and light playouts do not scale to Fuego with long thinking times on big hardware. I think the MoGo team has made similar observations.

	Martin