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## Re: [Bug-gnubg] Analyse -> Market Window question?

 From: Ian Shaw Subject: Re: [Bug-gnubg] Analyse -> Market Window question? Date: Tue, 11 Jun 2013 09:31:14 +0000

```The link to your screenshots do not work for me, I'm afraid.

-- Ian (more below)

> i.e. "it says my cube market window opens up at 50.286%... but I was around
> 55.7% to win the game at this point?" yet it says my cube decision was very
>
>
> Ian Shaw wrote
> > If this were the last roll of the game, and you would never get a
> > chance to double later, it would be correct to double.
>
> I would hope that the displayed data would be giving me relevant information
> on my market window with reference to my *current* move, not for the future
> last roll of the game?
>

The opening of the doubling window is a commonly understood, and calculable,
theoretical reference value. When you should actually double in practice is, I
think, more of a judgement call.

Obviously, gnubg has some hard rules about when to actually double. I don't
know what they are, but I believe they are based on Janowski's formulas, and
are quite complicated. They take into account the possible gammons and recubes
to the end of the match. They aren't something that humans tend to use in
actual play.

You do raise interesting points.  As experienced players and/or developers,
it's sometimes difficult to see what might be missing or confusing to a
newcomer. It probably would be useful to display the actual range at which you
should double. I suspect the reason it isn't displayed is that it's not
something that is calculated and used by a bot. The bot will simply double if
the equity from doubling exceeds the equity from not doubling. It doesn't
calculate a range of winning percentages, adjust for gammons and recubes,
estimate whether it's in this range, and then make a doubling decision - that's
what humans have to do, and that's what the values in the theory popup are
there to help with.

So yes, one answer is that you are a n00b and you don't understand what you are
looking at! Another answer is that the developers haven't made the popup
informative enough. Doubling theory is a tricky part of the game, and it's
possible that they haven't come up with a meaningful way of displaying what you
would like to see.

Disclaimer: I don't fully understand gnubg's doubling mechanisms myself, so
there may be someone out there who can give better information.

-- Ian

```