About
The Liesl Rule is a simple rule that gives cube action for 4 checkers on-roll versus a 3-roll position (i.e., 5 or 6 checkers stacked on the ace point). For example:
The Liesl Rule is described in Art Benjamin's "Math Overboard: Three Checkers Left and Variations" (PrimeTime Backgammon, Winter 2021). It is named after Liesl from The Sound of Music, who sings "Sixteen Going on Seventeen", since the rule involves the pip count range of 16-17.
How to use
Step 1: Compute Black's pip count
The Liesl rule is based on the pip count with no adjustments or penalties for stacked checkers. (There is a refinement discussed in the PrimeTime article based on the Adjusted Pip Count, but this is out of scope for this drill).
Step 2: Apply the Liesl Rule
If Black has 4 checkers and White has 5 or 6 checkers on the ace point, the Double/Take window is when Black's pip count is 16–17. In other words:
| Black's pip count | Cube action |
|---|
| 15 or less | Double/Pass |
| 16 or 17 | Double/Take |
| 18 or more | No Double/Take |
All doubles are also redoubles.