[Bug-gnubg] Move Ranking

[Christopher D. Yep]

Windows XP, GUI version
version 0.14-devel 1.1233 030801 (build Aug 1 2003)
[I haven't tried downloading the Aug 4 build yet.]

Position ID: v90IACDuDAAAAA
Match ID: QYkNAAAAAAAA
Player 0 = gnubg
Player 1 = any human

    GNU Backgammon  Position ID: v90IACDuDAAAAA
                    Match ID   : QYkNAAAAAAAA
    +24-23-22-21-20-19------18-17-16-15-14-13-+  O: gnubg (Cube: 2)
    | O  O  O  O       |   | O                |  0 points
    | O  O  O  O       |   |                  |
    | O     O          |   |                  |
    | O                |   |                  |
    | 6                |   |                  |
    |                  |BAR|                  |v
  X |                  |   |                  |
  X |                  |   |                  |
  X |    X  X          |   |                  |
 XX |    X  X     X    |   |                  |  Rolled 33
 XX | O  X  X     X    |   |                  |  0 points
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+  X: Chris

Use the tutor mode, e.g. here are some of the relevant commands from my 
.gnubgautorc:

set evaluation chequerplay type evaluation
set evaluation chequerplay evaluation plies 0
set evaluation chequerplay evaluation reduced 0
set evaluation chequerplay evaluation cubeful on
set evaluation chequerplay evaluation noise 0.000
set evaluation chequerplay evaluation deterministic on
set analysis threshold doubtful 0.040
set tutor mode on
set tutor cube on
set tutor chequer on
set tutor eval off
set tutor skill doubtful

[BTW, "set tutor eval off" means that tutor uses the evaluation settings 
and "set tutor eval on" means that tutor uses the analysis settings.  Would 
it make more sense to be the other way around or is this for historical 
reasons?]

Now, play 5/2(2) 3/off(2) in the GUI.  This is an error > .04 at 0-ply 
cubeful according to gnubg so the tutor window will pop-up ("You are about 
to make a doubtful play.  Are you sure?").  Click "Hint".  The hint window 
now pops up.  There are only two legal moves.  5/2 3/off(3) is ranked as 
the #1 move.  However 5/2(2) 3/off(2) has "??" listed in the rank column.

Note that when copying these moves from the hint window, 5/2(2) 3/off(2) 
correctly has rank 2:

    1. Cubeful 0-ply    5/2 3/off(3)                 Eq.:  +1.233
        97.3%  28.7%   0.9% -   2.7%   0.0%   0.0%
        0-ply cubeful [expert]
    2. Cubeful 0-ply    5/2(2) 3/off(2)              Eq.:  +1.182 ( -0.051)
        97.6%  23.4%   0.5% -   2.4%   0.0%   0.0%
        0-ply cubeful [expert]

Variations: the bug also occurs if I "set tutor eval on" or if I have the 
tutor evaluate plays at 2-ply cubeful instead of 0-ply cubeful, etc.  I.e. 
the bug seems to be mostly with the position and the generation of the 
movelist rather than the evaluation settings (just a guess).

Chris