Re: [Bug-gnubg] RE: Gammons in Jacoby game!

[Joern Thyssen]

On Tue, Aug 06, 2002 at 07:55:44PM +0000, Joern Thyssen wrote
> On Mon, Aug 05, 2002 at 04:52:16PM +0000, Joern Thyssen wrote
> >
> > > Further checks show that GnuBg thinks it has "Optional double, pass" from
> > > move 15 on. It should be cubing me out because it only has 72% wins and
> > > can't score a gammon.
> > > I think the new Optional Double logic has broken something.
> > 
> > Hmm, very strange. I found an error yesterday that would give exactly
> > this behaviour, but I checked in a patch at 10pm that fixed that.
> > I get "double, pass" at gnubg move #4 and forward...
> 
> Well, let me correct this: I get double, pass on 2-ply. On 0-ply I get
> exactly your problem....

I have a fix for this problem. I'll have to do some further testing
before I commit. Basically, the logic for determining a optional double,
pass is:

      /* 
       * the double is optional iff:
       * (1) equity(no double) = equity(drop)
       * (2) the player on can win gammon or backgammon
       * (3a) it's match play
       * or if it's money play
       * (3b) it's not a centered cube
       * or
       * (3c) the Jacoby rule is not in effect
       */

Jørn

-- 
Joern Thyssen, PhD
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