Re: Why such discrepancy for the ranked (obviously wrong) 1st choice between 4 ply and simulation ?

[Joseph Heled]

You can probably write a 5kg book about positions where a bot plays
different moves at 0-ply and 1-ply. No bot is good at all types of
positions.And remember, to get the higher plies the bot need to "play" the
position to this depth. With a tricky position many moves might be
inaccurate, so the higher ply is not always correct as well.
Same for rollouts.

-Joseph

On Mon, 2 Nov 2020 at 04:02, pierre zakia <pza...@yahoo.com> wrote:

> Hi everybody,
>
>
> In the position here below, I am curious to understand what in Gnubg
> engine yields such discrepancy between 4 ply and roll out.
>
>
> GNU Backgammon  ID de position: G27HAAiY2+ABAw
>
>                  ID de match   : MAHyAAAAAAAE
>
>  +12-11-10--9--8--7-------6--5--4--3--2--1-+     O: gnubg
>
>  |             O  O |   | O     O  X       |     0 point
>
>  |             O  O |   | O     O          |     Dés jetés 44
>
>  |                  |   | O                |
>
>  |                  |   |                  |
>
>  |                  |   |                  |
>
> ^|                  |BAR|                  |     Match en 7 points (Videau
> : 1)
>
>  |                  |   |                  |
>
>  | O                |   |                  |
>
>  | O           X    |   | X                |
>
>  | O  X        X  X |   | X  O        X  X |
>
>  | O  X        X  X |   | X  O        X  X |     0 point
>
>  +13-14-15-16-17-18------19-20-21-22-23-24-+     X: pierrez
>
>                     Pip counts : O 148, X 106
>
>
> *4 ply results *:
>
> *13/5 13/9(2)  *+0,579
>
> 0,684 0,135 0,005 - 0,316 0,098 0,002
>
> *20/16(2) 13/9(2) *+0,570 (* -0,008*)
>
> 0,675 0,083 0,003 - 0,325 0,082 0,001
>
> *13/5(2) *+0,436 ( -0,143)
>
> 0,611 0,122 0,003 - 0,389 0,065 0,001</td>
>
>
> *Roll out :*
> 1. Roll out       *20/16(2) 13/9(2)*             Eq.:  +0,783
>
>        0,709 0,078 0,003 - 0,291 0,089 0,000 CL  +0,415 CF  +0,783
>
>       [0,011 0,006 0,000 - 0,011 0,012 0,012 CL   0,026 CF   0,053]
>  2. Roll out       *13/5 13/9(2) *                Eq.:  +0,576 (* -0,207*)
>
>        0,675 0,138 0,004 - 0,325 0,101 0,002 CL  +0,389 CF  +0,576
>
>       [0,002 0,003 0,000 - 0,002 0,002 0,000 CL   0,004 CF   0,007]
>  3. Roll out       *13/5(2)   *                   Eq.:  +0,549 ( -0,233)
>
>        0,634 0,105 0,003 - 0,366 0,044 0,056 CL  +0,338 CF  +0,549
>
>       [0,008 0,009 0,001 - 0,008 0,007 0,055 CL   0,020 CF   0,049]
>
>
> I am more interested in the relative equity (bold font) between the first
> 2 moves than in the respective absolute equity of the same moves.
>
>
> Thanks in advance to shed some light on this.
>
>
> Pierre
>
>