Forum Archive : Cube Handling

Liveliness of the cube From:   Kit Woolsey Address:   kwoolsey@netcom.com Date:   7 April 1997 Subject:   Re: Liveliness of the cube Forum:   rec.games.backgammon Google:   kwoolseyE88w6E.B1C@netcom.com > I have a question concerning the liveliness of the cube. In a money > game, assuming a dead cube the takepoint is 25%; assuming a completely > alive cube the takepoint becomes 20%. Common wisdom says that the real > takepoint is something like 21.5% (corresponds to an equity of -0.57). > This would mean that one considers the cube to be alive to 70%. How > can we compute mathematically this number? No, we can't. It depends on the type of positions. Two examples: a) A long race. Here the trailer is likely to have a reasonably efficient recube if things go his way, so the cube is relatively alive. b) A holding game -- way behind in the race (so must hit a shot), but the trailer having a perfect prime which he will be able to maintain for several rolls. In this case, if the trailer does hit his shot he will suddenly become a huge favorite and lose his market by a mile. Thus, the cube is relatively dead. The above are examples of positions where gammons are impossible or very unlikely. If gammons are in the air, things get more complex still. For example, consider a blitz position. Assuming the trailer has a close pass/take decision, this means that his win percentage is way above 25% (to compensate for the many gammons he loses). Thus, he will be able to get in even more recubes than normal. Also, this type of position tends to lead to very efficient recubes when the game turns around, since usually the trailer makes his improvements slowly. Therefore, the cube is even more alive than normal. The 21.5% figure is the generally agreed figure for the "average" position. However, the actual number definitely depends on the position in question. > Also, in some scores for example 3-away 4-away the live takepoint is 19% > but the dead takepoint is around 34%, what is considered to be the real > takepoint? Instinctively, I would guess that the recube of the trailer is > more alive than usual due to the very high takepoint of 40% of the > redouble. Again, I would be very interested in how one could compute this > number. Yes, the cube is more alive than usual due to the takepoint of the redouble. And, once again, for the reasons above, there is no way to compute this number. Kit   Did you find the information in this article useful?           Do you have any comments you'd like to add?

 

Cube Handling

Against a weaker opponent  (Kit Woolsey, July 1994) 

Closed board cube decisions  (Dan Pelton+, Jan 2009) 

Cube concepts  (Peter Bell, Aug 1995) 

Early game blitzes  (kruidenbuiltje, Jan 2011) 

Early-late ratio  (Tom Keith, Sept 2003) 

Endgame close out: Michael's 432 rule  (Michael Bo Hansen+, Feb 1998) 

Endgame close out: Spleischft formula  (Simon Larsen, Sept 1999) 

Endgame closeout: win percentages  (David Rubin+, Oct 2010) 

Evaluating the position  (Daniel Murphy, Feb 2001) 

Evaluating the position  (Daniel Murphy, Mar 2000) 

How does rake affect cube actions?  (Paul Epstein+, Sept 2005) 

How to use the doubling cube  (Michael J. Zehr, Nov 1993) 

Liveliness of the cube  (Kit Woolsey, Apr 1997) 

PRAT--Position, Race, and Threats  (Alan Webb, Feb 2001) 

Playing your opponent  (Morris Pearl+, Jan 2002) 

References  (Chuck Bower, Nov 1997) 

Robertie's rule  (Chuck Bower, Sept 2006) 

Rough guidelines  (Michael J. Zehr, Dec 1993) 

Tells  (Tad Bright+, Nov 2003) 

The take/pass decision  (Otis+, Aug 2007) 

Too good to double  (Michael J. Zehr, May 1997) 

Too good to double--Janowski's formula  (Chuck Bower, Jan 1997) 

Value of an ace-point game  (Raccoon+, June 2006) 

Value of an ace-point game  (Øystein Johansen, Aug 2000) 

Volatility  (Chuck Bower, Oct 1998) 

Volatility  (Kit Woolsey, Sept 1996) 

When to accept a double  (Daniel Murphy+, Feb 2001) 

When to beaver  (Walter Trice, Aug 1999) 

When to double  (Kit Woolsey, Nov 1994) 

With the Jacoby rule  (KL Gerber+, Nov 2002) 

With the Jacoby rule  (Gary Wong, Dec 1997) 

Woolsey's law  (PersianLord+, Mar 2008) 

Woolsey's law  (Kit Woolsey, Sept 1996) 

Words of wisdom  (Chris C., Dec 2003) 

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