Mind the match cube!

[Axel Reichert]

GNU Backgammon Position ID: 2u4PAACtuysAAA
Match ID : AhlgAQAAIAAE
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ O: gnubg
| O O O O O O | | O O | 0 points
| O O O O | | |
| O O O | | |
| | | |
| | | |
| |BAR| |^
| 7 | | |
| X | | |
| X X | | |
| X X X X | | | Cube offered at 8
| X X X X X | | | 4 points
+24-23-22-21-20-19------18-17-16-15-14-13-+ X: axel
Pip counts: O 68, X 73

[MK]

On February 8, 2023 at 11:49:24 PM UTC-7, Axel Reichert wrote:

> GNU Backgammon Position ID: 2u4PAACtuysAAA
> Match ID : AhlgAQAAIAAE

I very rarely comment on positions and thus I ignore
almost all posts discussing positions but three out
of your last consecutive position decision posts being
about cube vs checker skill did catch my attention to
say a few words.

Since even your own experiments demonstrated that
cube magnifies luck, I can understand wht mentally
ill gamblers like you would focus more on that. Also
since it allows more "wiggle room" for bullshit...

Consider this: in classic backgammon, (i.e. cubeless),
amatch is a "two out of three" five-pointers, or rarely,
in the alternative, is a single seven-pointer. Frankly, I'm
not sure if winning a single seven-pointer is as hard as
winning two out of three five-pointers and I sure would
like to see an experiment done on this. But my point is
that a backgammon world championship can well be
decided by a two out of three cubeless five-pointers.

However, since cube promotes luck, a five-pointer or
even a seven-pointer gamblegammon match wouldn't
be long enough for luck to even out and skill to emerge.
Thus, gamblegammon world championships must be
determined by twentyfive-point matches! Again, I'm not
sure if winning a single cubeful twentyfive-pointer is as
hard as winning two out of three five-pointers and I sure
would like to see an experiment done on this also...!

One thing that is self evident about the cube's magnifying
luck is the need for long enough, (i.e. twentyfive-point),
matches in order for the luck to level out, (and thus the
only real skill, the "cube skill" skill to emerge out)...!

My interest in debunking the gamblegammon cube skill
comes and goes. I drafted an improved Murat mutant
experiment for you long time ago, that I couldn't gather
the will to finalize and post here but maybe this will be
an incentive to finally do it soon...

MK

[Axel Reichert]

Rollout cubeless equity +0.396 (Money: +0.396)

Cubeful equities:
1. Double, pass +1.000
2. Double, take +1.161 (+0.161)
3. No double +0.899 (-0.101)
Proper cube action: Redouble, pass

Rollout details:
Player gnubg owns 4-cube:
0.698 0.000 0.000 - 0.302 0.000 0.000 CL +0.396 CF +0.899
[0.001 0.000 0.000 - 0.001 0.000 0.000 CL 0.003 CF 0.002]
Player axel owns 8-cube:
0.698 0.000 0.000 - 0.302 0.000 0.000 CL +1.161 CF +1.161
[0.000 0.000 0.000 - 0.000 0.000 0.000 CL 0.000 CF 0.000]
Truncated cubeful rollout (depth 6) with variance reduction
36 games, Mersenne Twister dice gen. with seed 449002682 and quasi-random dice
Stop when std.errs. are small enough: limit 0.0100 (min. 36 games)
Play: world class 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 8 more moves within equity 0.16
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]
Different evaluations after 2 plies:
Play: 1-ply cubeful
keep the first 0 0-ply moves and up to 8 more moves within equity 0.16
Cube: 2-ply cubeful prune [world class]