Re: [Bug-gnubg] Too good to double when a gammon is impossible?!

[Christian Anthon]

This happens when the evaluation is bad enough to allow for bad takes later.

Christian.

On Fri, Aug 21, 2009 at 9:48 PM, Timothy Y. Chow<address@hidden> wrote:
> I just rolled out a cube decision and gnubg evaluated "no double" at greater
> than +1.000 equity despite the fact that a gammon was no longer possible.
>  Below is the text output; I can email the .sgf file if anyone
> wants it.
>
> Tim
>
>
> The score (after 0 games) is: gnubg 0, tchow 0
> Match Information:
>
> Date: 08/21/2009
> Move number 1:  gnubg on roll, cube decision?
>
>  GNU Backgammon  Position ID: bgAAULZtEwAiAA
>                 Match ID   : AQEAAAAAAAAA
>  +12-11-10--9--8--7-------6--5--4--3--2--1-+     O: gnubg (Cube: 2)
>  |          O     O |   | O  O  O  O  O  X |     0 points
>  |                O |   | O  O  O  O  O    |     On roll
>  |                  |   |                  |
>  |                  |   |                  |
>  |                  |   |                  |
> ^|                  |BAR|                  |
>  |                  |   |                  | X
>  |                  |   |                  | X
>  |                  |   |             X    | XX
>  |                  |   |          X  X    | XX
>  |                  | X |       O  X  X  O | XX  0 points
>  +13-14-15-16-17-18------19-20-21-22-23-24-+     X: tchow
> Pip counts: O 108, X 61
>
> * gnubg doubles
>
> Alert: wrong double ( -0.167)!
> Rollout details:
> Player gnubg owns 2-cube:
>  0.828 0.000 0.000 - 0.172 0.007 0.001 CL  +0.647 CF  +1.167
>  [0.002 0.000 0.000 - 0.002 0.000 0.000 CL   0.004 CF   0.010]
> Player tchow owns 4-cube:
>  0.859 0.000 0.000 - 0.141 0.006 0.001 CL  +1.422 CF  +1.325
>  [0.002 0.000 0.000 - 0.002 0.000 0.000 CL   0.008 CF   0.010]
> Full cubeful rollout with var.redn.
> 1296 games, Mersenne Twister dice gen. with seed 866958217 and quasi-random
> dice
> Play: 0-ply cubeful [expert]
> Cube: 0-ply cubeful [expert]
>
>
>
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