I see, that's very interesting. I'll make sure not to use ctrl-g for skewed
situations like this!
So the real problem is that it thinks that gammon chances are near 0 for a
position like this, when in fact it is 25%:
GNU Backgammon Position ID: h+sPAQD3rQEAAA
Match ID : EAEAAAAAAAAE
+12-11-10--9--8--7-------6--5--4--3--2--1-+ O: gnubg
| | | O O O O O | O 0 points
| | | O O O O | O On roll
| | | O O |
| | | O |
| | | O |
^| |BAR| |
| 7 | | |
| X | | |
| X | | X X |
| X | | X X |
| X X | | X X X | 0 points
+13-14-15-16-17-18------19-20-21-22-23-24-+ X: aaron (Cube: 1)
I'm not an expert but I'd think the NN should be able to learn this better -
why not just try to train it more?
Is gnubg currently able to keep a database of its own 0-ply blunders? (Like,
every time it does an evaluation, compare the higher-ply result with the 0-ply
result and if the 0-ply errs by a large enough threshhold, add the position to
the database.) If not, do you think it would be worth implementing this?
Best regards, Aaron
________________________________
From: Øystein Schønning-Johansen <[email protected]>
Sent: October 19, 2020 9:26 AM
To: Aaron Tikuisis <[email protected]>
Cc: Joseph Heled <[email protected]>; Philippe Michel
<[email protected]>; [email protected] <[email protected]>
Subject: Re: The status of gnubg?
Attention : courriel externe | external email
On Mon, Oct 19, 2020 at 3:10 PM Aaron Tikuisis
<[email protected]<mailto:[email protected]>> wrote:
That is interesting, I did not realize that gnubg misplays race positions much.
What are some examples?
Here is a position I posted a few weeks ago.
GNU Backgammon Position ID: 960BAMCw+0MAAA
Match ID : cAkAAAAAAAAA
+13-14-15-16-17-18------19-20-21-22-23-24-+ O: gnubg
| | | O O O O O | O 0 points
| | | O O O O | O
| | | O O |
| | | O |
| | | O |
v| |BAR| | (Cube: 1)
| 7 | | |
| X | | |
| X | | X |
| X | | X X X | On roll
| X X | | X X X | 0 points
+12-11-10--9--8--7-------6--5--4--3--2--1-+ X: oystein
Money game and X to play. Try several rolls, like 52, 31 and 53 and... at
0-ply. What's the best move? 52: 6/1 6/4?
Of course, the evaluator reports 0.0 win, but since the gammons are incorrectly
evaluated by the neural network, it makes ridiculous moves.
It looks like this is a common pattern in positions which are "skewed".
-Øystein
