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GnuBG Full rollout bugged?

Posted By: Carlo Melzi
Date: Monday, 18 May 2009, at 9:01 a.m.

I ran into this position last week in a local club superjackpot. I was playing Blue and, behind 1-7 to 11, I doubled and White passed.

The score (after 0 games) is: Blue 7, White 1 (match to 11 points)

Move number 2: White on roll, cube decision?

Blue	94
White	149
Position ID: cP8BAJBtGwCwBQ Match ID: cAlgAXAACAAA

There was some discussion afterwards, with some people agreeing with the pass and some other pointing out a clear take.

I tried some 1296 full 2-ply rollouts with GnuBG and all of them result in something like this:

Rollout 2-ply Double, Pass +1,000 Double, Take +1,138 No Double +1,117 Correct Cube action: Double, Pass

I don't have the rollout details here, but does this make sense to you?

After the rollout, GnuBG says Double/Pass, but according to the cubeful equities, the correct decision seems to be... TGTD/Pass!?!?

The equity for Not doubling cannot be greater than 1, since Blue cannot win gammon here!

Does anybody feel like trying a full rollout of the position with GnuBG and verify whether GnuBG has a bug in full rollouts?

Thanks, Carlo

Messages In This Thread

• GnuBG Full rollout bugged?
  Carlo Melzi -- Monday, 18 May 2009, at 9:01 a.m.
  • GnuBG Full rollout bugged?
    misja -- Monday, 18 May 2009, at 9:17 a.m.
    • GnuBG Full rollout bugged?
      Carlo Melzi -- Monday, 18 May 2009, at 9:24 a.m.
  • GnuBG Full rollout bugged?
    Bob Koca -- Monday, 18 May 2009, at 11:57 a.m.
    • GnuBG Full rollout bugged?
      Carlo Melzi -- Monday, 18 May 2009, at 3:25 p.m.
  • GnuBG Full rollout bugged?
    neilkaz -- Monday, 18 May 2009, at 12:57 p.m.
    • GnuBG Full rollout bugged?
      Carlo Melzi -- Monday, 18 May 2009, at 3:10 p.m.
      • GnuBG Full rollout bugged?
        neilkaz -- Monday, 18 May 2009, at 6:02 p.m.