Hi Mochizuki and Massimiliano,
Looks like the issues got confused here a little.
First of all, GNUbg's win/gammons/backgammons breakdown is based on what
happens or would happen if the game were played to completion. A double/pass
is therefore not the same as a single game win. A double/pass will be scored
in the w/g/bg columns using the evaluation at that point.
So, like Christian's example, a double/pass could happen with 60% winning
chances and 40% gammon chances. Cubeful it will be scored as +1 (in EMG),
but it won't be scored in the w/g/bg breakdown as a 100% single win, but
rather using the actual evaluation figures.
Second, GNUbg's cubeful rollout is what you want it to be, whether it's a
cube decision or checker play decision. It plays with a fully live cube, and
uses cubeful evaluations along the way (assuming that box is checked in the
settings, as it should be for anything cubeful).
On Nov 13, 2007 11:14 AM, Massimiliano Maini <[EMAIL PROTECTED]>
wrote:
1- When you say "cubeless", do you mean that the game will be truncated
> right after the very first double decision, if any? I understand your
> example of a double/pass, but what about a double/take situation?
>
A cubeful rollout trial will be truncated whenever GNUbg thinks it's a
(re)double/pass. The reason is simply this: the cubeful equity is known at
that point: +1 in EMG. Also, in a real game, play would be over when one
side passes: GNUbg works the same way. For the w/g/bg breakdown and cubeless
equity figure, the values from the cube evaluation at that point are used.
When a (re)double/take happens, the trial just continues, since the cubeful
equity isn't known at that point. The new cube value and position will be
taken into account ("fully live cube").
> 2- At the end of the trials, the computed "cubeless" figures will
> lead to a "cubeless" equity that will be translated into a cubefull
> equity via the janowski formula, right?
No. GNUbg currently has no such feature. Either it's a cubeless rollout and
only gives you a cubeless equity, or it's a cubeful rollout and uses a live
cube to determine cubeful equity (not a Janowski approximation).
It might be a nice feature though, to have GNUbg give us a Janowski cubeful
equity in cubeless rollouts, handy for those positions where GNUbg's cube
actions in a rollout lead to many (quick) incorrect double/passes (with the
associated wrong w/g/bg breakdowns...). I think Jellyfish uses this
approach, and Snowie also has it as a feature ("cubeful" equity in a
cubeless, i.e. no live cube rollout).
> In Mochy's example, the W/G/BG%
> are the "cubeless" results of the rollout, the CL is the "cubeless"
> equity and CF is comuted via Janowski formula?
So, no.
>
>
> > > Rollout details:
> > > Centered 1-cube:
> > > 0.669 0.146 0.002 - 0.331 0.078 0.003 CL +0.405 CF +0.621
> > > Player player owns 2-cube:
> > > 0.670 0.152 0.001 - 0.330 0.077 0.003 CL +0.854 CF +0.574
>
> 3- Any idea why a simple "full cubefull rollout" approach is not
> implemented ?
> I mean letting gnubg play against himeself cubefull and record the
> outcome.
So, this is what a GNUbg cubeful rollout does.
>
> I suspect this comes from the fact that its result would not be a W/G/BG%
> but more an equity (for money) or a MWC (for match), but hey, these
> are what matters ...
The w/g/bg are still basically the same (as they would be in a cubeless
("dead cube") rollout), except that any (re)double/passes during the rollout
will use the evaluation breakdown at that point (i.e. truncated). The "live
cube" is reflected in the cubeful equity.
> Another reason is that the current method, truncating at double decisions,
> should/could "reduce the variance" (provided the evaluation is good).
>
So the truncating only happens when it's a (re)double/pass. This reduces
variance and speeds up the rollout.
HTH,
--
Robert-Jan Veldhuizen
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