Re: [Bug-gnubg] I'm a bit confused

[Joern Thyssen]

On Wed, Jul 30, 2003 at 07:35:47AM +0000, Joern Thyssen wrote
> 
> Worst case scenario: you're on roll in a position where you'll be
> doubled out no matter what you roll. If you do a 0-ply cubeful rollout
> then the cubeful equity is -1 and the cubeless gwc is identical to a
> cubeless 0-ply evaluation even though you've selected 1,679,616 trials.
> ^^^^^^^^^^^^^^
> 
>  GNU Backgammon  Position ID: tm0DBwDgc/ABMA Match ID   : cIkIAAAAAAAA
>  +13-14-15-16-17-18------19-20-21-22-23-24-+     O: gnubg
>  | X              O |   | O  O  O  O  O  X |     0 points
>  | X              O |   | O  O  O  O  O  X |     
>  | X                |   |                  |     
>  | X                |   |                  |     
>  | X                |   |                  |    
> v|                  |BAR|                  |     (Cube: 1)
>  |                  |   | X                |    
>  |                  |   | X                |     
>  | O           X    |   | X                |     
>  | O           X    |   | X                |     Rolled 12
>  | O           X    |   | X                |     0 points
>  +12-11-10--9--8--7-------6--5--4--3--2--1-+     X: jth
> 
> 0-ply cubeful rollout:
> 
>     1. Rollout          6/5 6/4                      Eq.:  -1.000
>        0.211 0.017 0.000 - 0.789 0.295 0.016 CL  -0.872 CF  -1.000
>       [0.000 0.000 0.000 - 0.000 0.000 0.000 CL   0.000 CF   0.000]
>         Truncated cubeful rollout (depth 11) with var.redn.
>         1296 games, Mersenne Twister dice gen. with seed 1175268096 and
> quasi-random dice
>         Play: 0-ply cubeful [expert]
>         Cube: 0-ply cubeful [expert]
>     2. Rollout          8/7 6/4                      Eq.:  -1.000 (
> +0.000)
>        0.203 0.016 0.000 - 0.797 0.293 0.015 CL  -0.887 CF  -1.000
>       [0.000 0.000 0.000 - 0.000 0.000 0.000 CL   0.000 CF   0.000]
>         Truncated cubeful rollout (depth 11) with var.redn.
>         1296 games, Mersenne Twister dice gen. with seed 1175268096 and
> quasi-random dice
>         Play: 0-ply cubeful [expert]
>         Cube: 0-ply cubeful [expert]
> 
> 0-ply cubeless:
> 
>     1. Cubeless 0-ply   6/5 6/4                      Eq.:  -0.872
>        0.211 0.017 0.000 - 0.789 0.295 0.016
>         0-ply cubeless
>     2. Cubeless 0-ply   8/7 6/4                      Eq.:  -0.887 ( -0.015)
>        0.203 0.016 0.000 - 0.797 0.293 0.015
>         0-ply cubeless
> 
> Exactly the same gwcs as I predicted!

Here's the result of a 46,656 trial rollout:

    1. Rollout          6/5 6/4                      Eq.:  -1.000
       0.211 0.017 0.000 - 0.789 0.295 0.016 CL  -0.872 CF  -1.000
      [0.000 0.000 0.000 - 0.000 0.000 0.000 CL   0.000 CF   0.000]
        Truncated cubeful rollout (depth 11) with var.redn.
        46656 games, Mersenne Twister dice gen. with seed 1175269376 and
quasi-random dice
        Play: 0-ply cubeful [expert]
        Cube: 0-ply cubeful [expert]
    2. Rollout          8/7 6/4                      Eq.:  -1.000 (
+0.000)
       0.203 0.016 0.000 - 0.797 0.293 0.015 CL  -0.887 CF  -1.000
      [0.000 0.000 0.000 - 0.000 0.000 0.000 CL   0.000 CF   0.000]
        Truncated cubeful rollout (depth 11) with var.redn.
        46656 games, Mersenne Twister dice gen. with seed 1175269376 and
quasi-random dice
        Play: 0-ply cubeful [expert]
        Cube: 0-ply cubeful [expert]


It'll leave it to someone else to do the 1,679,616 trial rollout from my
example.

Note that the SD is zero for the rollout since all trials return the
same equity and gwcs.

Jørn