[Bug-gnubg] Incorrect equities calculated

[Jim Blue]

In the saved position below, the equities at 2-ply and roll-out are reasonable, in the neigherborhood of -.5, but at 3-ply they all come out to be -1. (I set up this position by editing it, not in the course of a game, in case that matters.)

 

My settings for both Analysis and Evaluation are World Class, 2 plies, no reduction, cubeful, 0 noise, move filter normal.

 

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GnuBG (O, 0 pts) vs. Jim (X, 0 pts) (Match to 3)

 

Game number 1

 

Match Information:

 

GnuBG's rating: n/a
Jim's rating: n/a
Date: August 07, 2003
Event: n/a
Round: n/a
Place: n/a
Annotator: n/a
Comments: n/a
Move number 4: X to play 15

 

    GNU Backgammon  Position ID: 7LwDBwC03YQBAw
                    Match ID   : cIl0AAAAAAAA
    +24-23-22-21-20-19------18-17-16-15-14-13-+  O: GnuBG
    |       O  O  X  O |   | O              X |  0 points
    |       O  O  X  O |   | O              X | 
    |          O     O |   | O                | 
    |                O |   |                  | 
    |                  |   |                  | 
    |                  |BAR|                  |v 3 point match (Cube: 1)
    |                  |   |                  | 
    |                  |   |                  | 
    |                X |   |                O | 
    |          X  X  X |   | X              O |  Rolled 15
    |       X  X  X  X |   | X     X        O |  0 points
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+  X: Jim
Pip counts: O 102, X 128

 

 

 

Cube analysis
2-ply cubeless equity  -0.488 (Money:  -0.480)
  0.266 0.013 0.000 - 0.734 0.025 0.001
Cubeful equities:
1. No double            -0.933
2. Double, pass         +1.000  ( +1.933)
3. Double, take         -2.372  ( -1.439)
Proper cube action: No double, take (42.7%)

 

Rolled 15:     1. Rollout          7/6 7/2                      Eq.:  -0.532
       0.240 0.011 0.000 - 0.760 0.018 0.001 CL  -0.532
      [0.002 0.001 0.000 - 0.002 0.001 0.000 CL   0.005]
        Truncated cubeless rollout (depth 11) (trunc. at one-sided bearoff) with var.redn.
        108 games, Mersenne Twister dice gen. with seed 1176041872 and quasi-random dice
        Play: 0-ply cubeful
        Cube: 0-ply cubeful
     2. Cubeful 3-ply    9/8 7/2                      Eq.:  -1.000 ( -0.468)
       0.254 0.013 0.000 - 0.746 0.027 0.001
     3. Cubeful 3-ply    7/2 6/5                      Eq.:  -1.000 ( -0.468)
       0.254 0.014 0.000 - 0.746 0.027 0.001
     4. Cubeful 3-ply    7/2 4/3                      Eq.:  -1.000 ( -0.468)
       0.254 0.013 0.000 - 0.746 0.027 0.000
     5. Cubeful 3-ply    7/2 3/2                      Eq.:  -1.000 ( -0.468)
       0.254 0.013 0.000 - 0.746 0.027 0.001

 

Output generated Thu Aug 07 15:06:42 2003
by GNU Backgammon 0.14-devel 1.1245 030805 (Text Export version 1.50)