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eXtreme Gammon — Cubeless versus No Cube

Posted By: Taper_Mike
Date: Wednesday, 24 July 2013, at 6:25 a.m.

In Response To: Basic ace deuce backgame cube (Bob Koca)

In XG Help, under Options, I find this description of a cubeless rollout:

Cubeless rollout: When used the games are rolled without any player doubling (note that moves are still made with the score in mind). When the rollout is completed the cubeless evaluation is transformed into cubeful.

Evidentally, “transform” means to apply the Janowski formula.

You can select this sort of cubeless rollout by opening the Rollout tab of the Options and Settings dialog box. There you will find a checkbox labeled “Cube decisions: Cubeless.” The same checkbox is available when you make an “Ad hoc” rollout. When you export such a rollout, the word “Cubeless” will be listed among the rollout parameters.

Another sort of cubeless rollout should be used when players do not use the cube at all. For this, go to the Setup menu, and choose “Maximum Cube Value: Cubeless.” When this setting is selected, the final number at the end of the XGID will be 0. That's the field used for “maximum cube turns.”

Be very careful with this. If you forget to remove the checkmark for Jacoby (in a money game), you will also find that no gammons or backgammons are possible. The result of such a setting is to produce a DMP rollout (no cube, no gammons, no backgammons). I learned this the hard way in my rollout of 51S-42P-32. I rerolled it—without Jacoby—to create a no-cube rollout where gammons and backgammons are still possible. My no-cube rollout does not list the word “Cubeless” among its rollout parameters.

Does the Jacoby checkbox impact cubeless rollouts in a similar way? I do not know. I did notice, however, that MCG took the trouble to remove the checkmark from Jacoby in the cubeless rollout he posted today. He also set the “Maximum Cube Value” to zero, as can be seen in his XGID. Because the rollout parameters include the word “Cubeless,” we also know that he placed a checkmark in the “Cube decisions: Cubeless” checkbox.

Looking at the rollout in the post by Rew, I see that Jacoby is selected. Does that mean that no gammons or backgammons were awarded? Once again, I do not know. I also see, in the XGID, that the normal 10 cube turns were allowed. Because the word “Cubeless” appears, we know Rew placed a checkmark in the “Cube decisions: Cubeless” checkbox.

I used a few combinations of the settings below. As I was finishing up, I noticed that none have Variance Reduction. Whoops. No harm done, however, because they only have 324 trials anyway. I just wanted to see whether the resulting equities would match or not. From what I am seeing, it looks like MCG’s rollout was of the no-cube variety, while Rew’s was Janowski adjusted in some manner. I am still not clear how gammons and backgammons are dealt with in the rollout by Rew.

So now the question arises, just what sort of cubeless rollout did you intend?

Mike


Cubeless, Jacoby, Max cube turns = 10





White is Player 2

score: 0
pip: 160
Unlimited Game
Jacoby Beaver
pip: 58
score: 0

Blue is Player 1
XGID=-bbFED-----------bbcbb----:0:0:1:61:0:0:3:0:10
Blue to play 61
1.Rollout15/4 5/Offeq: +0.5496
Player:
Opponent:
52.47% (G:32.41% B:9.26%)
47.53% (G:0.00% B:0.00%)
Conf.: ±0.1038 (+0.4458...+0.6534) - [100.0%]
Duration: 55.0 seconds
2.Rollout15/Off 4/3eq: +0.1940 (-0.3556)
Player:
Opponent:
44.14% (G:26.54% B:6.79%)
55.86% (G:0.00% B:0.00%)
Conf.: ±0.1028 (+0.0912...+0.2969) - [0.0%]
Duration: 52.3 seconds
 
1 324 Games rolled.
Dice Seed: 87256214
Cubeless
Moves: 3-ply

eXtreme Gammon Version: 2.10


Cubeless, no Jacoby, Max cube turns = 10





White is Player 2

score: 0
pip: 160
Unlimited Game
pip: 58
score: 0

Blue is Player 1
XGID=-bbFED-----------bbcbb----:0:0:1:61:0:0:0:0:10
Blue to play 61
1.Rollout15/4 5/Offeq: +0.6046
Player:
Opponent:
51.85% (G:33.02% B:9.57%)
48.15% (G:0.00% B:0.00%)
Conf.: ±0.1540 (+0.4506...+0.7587) - [99.9%]
Duration: 46.3 seconds
2.Rollout15/Off 4/3eq: +0.2726 (-0.3320)
Player:
Opponent:
45.68% (G:25.93% B:5.86%)
54.32% (G:0.00% B:0.00%)
Conf.: ±0.1456 (+0.1270...+0.4182) - [0.1%]
Duration: 43.9 seconds
 
1 324 Games rolled.
Dice Seed: 87256214
Cubeless
Moves: 3-ply

eXtreme Gammon Version: 2.10


Cubeless, no Jacoby, Max cube turns = 0





White is Player 2

score: 0
pip: 160
Unlimited Game
pip: 58
score: 0

Blue is Player 1
XGID=-bbFED-----------bbcbb----:0:0:1:61:0:0:0:0:0
Blue to play 61
1.Rollout15/4 5/Offeq: +0.4475
Player:
Opponent:
52.16% (G:32.10% B:8.33%)
47.84% (G:0.00% B:0.00%)
Conf.: ±0.1503 (+0.2973...+0.5978) - [98.9%]
Duration: 31.4 seconds
2.Rollout15/Off 4/3eq: +0.2006 (-0.2469)
Player:
Opponent:
43.52% (G:26.54% B:6.48%)
56.48% (G:0.00% B:0.00%)
Conf.: ±0.1486 (+0.0520...+0.3492) - [1.1%]
Duration: 29.6 seconds
 
1 324 Games rolled.
Dice Seed: 87256214
Cubeless
Moves: 3-ply

eXtreme Gammon Version: 2.10


Not Cubeless, no Jacoby, Max cube turns = 0





White is Player 2

score: 0
pip: 160
Unlimited Game
pip: 58
score: 0

Blue is Player 1
XGID=-bbFED-----------bbcbb----:0:0:1:61:0:0:0:0:0
Blue to play 61
1.Rollout15/4 5/Offeq: +0.4475
Player:
Opponent:
52.16% (G:32.10% B:8.33%)
47.84% (G:0.00% B:0.00%)
Conf.: ±0.1503 (+0.2973...+0.5978) - [98.9%]
Duration: 30.9 seconds
2.Rollout15/Off 4/3eq: +0.2006 (-0.2469)
Player:
Opponent:
43.52% (G:26.54% B:6.48%)
56.48% (G:0.00% B:0.00%)
Conf.: ±0.1486 (+0.0520...+0.3492) - [1.1%]
Duration: 29.1 seconds
 
1 324 Games rolled.
Dice Seed: 87256214
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.10

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