Re: [Bug-gnubg] I'm a bit confused

[Jim Segrave]

On Wed 30 Jul 2003 (07:35 +0000), Joern Thyssen wrote:
> On Wed, Jul 30, 2003 at 12:07:13AM +0200, Jim Segrave wrote
> > > 
> > > You may see similar problems for evaluations as well, but as evaluations
> > > are never truncated then the problem is usually not so large.
> > 
> > Now I'm confused - I would think that the wins/gammons/backgammons
> > figures are accurate, but probably not complete enough. In the
> > situation you describe where you'll be doubled out, your wins should
> > be 0.0, lose gammon and lose backgammon will be either 0.0 or 1.0
> > depending on where your pieces are.
> 
> NO! If the rollout is truncated at "double, pass" gnubg uses the
> cubeless gwcs from the cube decision leading to "double, pass", It does
> *NOT* use 1 0 0 0 0!!!  "1 0 0 0 0" is a *cubeful* gwc and we can't mix
> that with the cubeless gwcs from the other trials.

OK - I haven't looked at BasicCubefulRollout in detail and I naively
assumed that it would use 1 0 0 0 0 0 when it concluded the player on
roll would double the opponent out. I've also been assumming that for
cubeful rollouts, when games are rolled out to completion, the cubeful
equity was adjusted by crediting the winner with a win/gammon/bg and
calculating the delta to the accumulating cubeful equity based on the
current cube value. And for games being truncated that the evaluation
at the truncation point was given a cubeful adjustment and then
factored in to the accumulated rollout stats.


-- 
Jim Segrave           address@hidden