[Bug-gnubg] 2 ply and closed out

[W.Stroop]

Hi there,

In the attached position 'user' has to play 5 3. For us "humans" it's easy
to come up
with the right move: 6 /1 and 6 / 3, since only 66 and 55 will leave a shot.
After
5 /off and  6 / 3  however  66 ,55,  65 and  64 will leave a shot.

On 2 ply analyses GNUbg produces this:
    1. Cubeful 2-ply    6/3 5/off                    Eq.:  +1,986
       0,938 0,685 0,003 - 0,062 0,000 0,000
        2-ply cubeful 100% speed [world class]
    2. Cubeful 2-ply    6/3 6/1                      Eq.:  +1,948 ( -0,037)
       0,959 0,638 0,002 - 0,041 0,000 0,000
        2-ply cubeful 100% speed [world class]

It appears that, if one player is dancing, it's not enough to perform a 2
ply analyse.

On 3 ply GNUbg produces the right move:

    1. Cubeful 3-ply    6/3 6/1                      Eq.:  +1,756
       0,948 0,536 0,001 - 0,052 0,000 0,000
        3-ply cubeful
    2. Cubeful 3-ply    6/3 5/off                    Eq.:  +1,737 ( -0,019)
       0,915 0,571 0,001 - 0,085 0,000 0,000
        3-ply cubeful

Greetings Rob

closedout.sgf
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