[Bug-gnubg] Strange move on 0-ply

[Ian Shaw]

0.13 weights Jan 19 2003

    GNU Backgammon  Position ID: zx4AALjbFgCBAA
                    Match ID   : MAFgACAAEAAA
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+  O: GnuBg
    | O  O  O  O  O  O |   |                  |  2 points
    | O  O  O  O  O    |   |                  |  On roll
    | O  O             |   |                  |  
    |                  |   |                  |  
    |                  |   |                  |  
    |                  |BAR|                  |^ 3 point match (Cube: 1)
  X |                  |   |                  |  
  X | X        X       |   |                  |  
  X | X        X       |   |                  |  
  X | X     X  X       |   |                  |  
  X | X  O  X  X       |   |    O             |  2 points
    +24-23-22-21-20-19------18-17-16-15-14-13-+  X: Ian

GnuBg gave up here, and ran with 23/16, despite knowing it was certain to lose 
if it did so, and also give up more gammons.

What gives? Move filters shouldn't have anything to do with it on 0-ply, should 
they?

    1. Cubeful 0-ply    17/10                        Eq.:  -0.909
       0.045 0.000 0.000 - 0.955 0.130 0.000
        0-ply cubeful [expert]
    2. Cubeful 0-ply    17/11 2/1                    Eq.:  -0.918 ( -0.009)
       0.041 0.000 0.000 - 0.959 0.148 0.001
        0-ply cubeful [expert]
    3. Cubeful 0-ply    17/11 6/5                    Eq.:  -0.928 ( -0.019)
       0.036 0.000 0.000 - 0.964 0.144 0.000
        0-ply cubeful [expert]
    4. Cubeful 0-ply    17/11 5/4                    Eq.:  -0.935 ( -0.026)
       0.032 0.000 0.000 - 0.968 0.152 0.001
        0-ply cubeful [expert]
    5. Cubeful 0-ply    17/11 4/3                    Eq.:  -0.937 ( -0.028)
       0.031 0.000 0.000 - 0.969 0.152 0.001
        0-ply cubeful [expert]
    6. Cubeful 0-ply    17/11 3/2                    Eq.:  -0.948 ( -0.038)
       0.026 0.000 0.000 - 0.974 0.156 0.001
        0-ply cubeful [expert]
    7. Cubeful 0-ply    23/17 5/4                    Eq.:  -1.000 ( -0.091)
       0.000 0.000 0.000 - 1.000 0.200 0.000
        0-ply cubeful [expert]
    8. Cubeful 0-ply    23/17 4/3                    Eq.:  -1.000 ( -0.091)
       0.000 0.000 0.000 - 1.000 0.207 0.000
        0-ply cubeful [expert]
    9. Cubeful 0-ply    23/17 3/2                    Eq.:  -1.000 ( -0.091)
       0.000 0.000 0.000 - 1.000 0.202 0.000
        0-ply cubeful [expert]
   10. Cubeful 0-ply    23/17 6/5                    Eq.:  -1.000 ( -0.091)
       0.000 0.000 0.000 - 1.000 0.204 0.000
        0-ply cubeful [expert]
   11. Cubeful 0-ply    23/16                        Eq.:  -1.000 ( -0.091)
       0.000 0.000 0.000 - 1.000 0.162 0.000
        0-ply cubeful [expert]

Player 0:
  Name: GnuBg
  Type: gnubg:
    Checker play:
      Neural net evaluation:
        0-ply evaluation.
        100% speed.
        Cubeless evaluations.
        Noiseless evaluations (deterministic noise).

    Move filters:
      Move filter for 1 ply:
        keep the first 8 0-ply moves
      Move filter for 2 ply:
        keep the first 2 0-ply moves and up to 3 more moves within equity 0.1
        keep the first 0 1-ply moves
      Move filter for 3 ply:
        keep the first 16 0-ply moves
        keep the first 4 1-ply moves
        keep the first 0 2-ply moves
      Move filter for 4 ply:
        keep the first 8 0-ply moves
        keep the first 0 1-ply moves
        keep the first 2 2-ply moves and up to 3 more moves within equity 0.1
        keep the first 0 3-ply moves

    Cube decisions:
      Neural net evaluation:
        0-ply evaluation.
        100% speed.
        Cubeless evaluations.
        Noiseless evaluations (deterministic noise).