Re: A very old bug reported on RGB

[Philippe Michel]

On Wed, Sep 14, 2022 at 08:22:00PM +0000, playbg-rgb@yahoo.com wrote:
> https://groups.google.com/g/rec.games.backgammon/c/kJM9O57Lu8Y/m/ZF7bkiQgBQAJ
> 
> On September 12, 2022 at 9:58:31 AM UTC+2, MK wrote:
> 
> > I set one player to Grandmaster checker and cube, one player
> > to Grandmaster checker and cube level to below beginner with
> > maximum noise. After letting it run for a dozen games, I checked
> > the stats to see how things were going. What did I see..? This..!
> > ===================================================
> > ....
> > Error rate mEMG (Points) -132.0 ( -0.318) -141.3 ( -0.186)
> > Cube decision rating Awful! Awful!
> > ===================================================
> 
> Thinking that this bug may not be in earlier versions, I went
> right to the oldest version I have: 0.15 from (15 years ago).
> And the bug has been there since then. What a shame... :(
> Not for the bug having never been fixed for that long but for
> nobody having discovered it since that time! Apparently I'm
> the only one to question the things that I question, look for
> answers and find bugs instead.


I don't know how exactly MK set up the play levels, but I cannot 
reproduce this kind of result. I get the expected result, with the 
player using 3 ply for cube decisions playing "perfectly":

Cube Statistics:
...
Wrong takes (EMG (Points))              1 (-0.014 ( -0.112))   0                
 
Wrong passes (EMG (Points))             0                    0
Error total EMG (Points)                   -0.014 ( -0.112)      -0.618 ( 
-0.618)
Error rate mEMG (Points)                   -2.0   ( -0.016)     -15.8   ( 
-0.016)
Cube decision rating                  Supernatural         Intermediate        

The -0.014 is apparently due to the "error" being a take in a double / 
beaver / raccoon / beaver / take sequence instead of beavering 
forever. If I play a match instead of a money session the cube error 
is exactly 0.

I started gnubg on a linux machine from a terminal, so I get the 
sequence of commands corresponding to the GUI choices:

(No game) set player 0 gnubg
(No game) set player 0 chequer evaluation plies 3
(No game) set player 0 movefilter 1 0 0 16 0.320
(No game) set player 0 movefilter 2 0 0 16 0.320
(No game) set player 0 movefilter 3 0 0 16 0.320
(No game) set player 0 movefilter 3 2 0 4 0.080
(No game) set player 0 movefilter 4 0 0 16 0.320
(No game) set player 0 movefilter 4 2 0 4 0.080
(No game) set player 0 cube evaluation plies 3
(No game) set player 1 gnubg
(No game) set player 1 chequer evaluation plies 3
(No game) set player 1 movefilter 1 0 0 16 0.320
(No game) set player 1 movefilter 2 0 0 16 0.320
(No game) set player 1 movefilter 3 0 0 16 0.320
(No game) set player 1 movefilter 3 2 0 4 0.080
(No game) set player 1 movefilter 4 0 0 16 0.320
(No game) set player 1 movefilter 4 2 0 4 0.080
(No game) set player 1 cube evaluation plies 0
(No game) set player 1 cube evaluation prune off
(No game) set player 1 cube evaluation noise 1.000

As far as I can tell the GUI sets the parameters correctly and the 
evaluation function uses them as expected.