The doubling cube.

Checker play decides where the game goes. The cube decides how much that journey is worth. Strong cube action depends on winning chances, gammons, volatility, ownership, and match score - not on a single fixed percentage.

What the cube changes

A game begins at one point with the cube centered. Before rolling, either player may offer a double while the cube is centered. The opponent must take and continue for twice the stakes or pass and lose the current value. After a take, the taker owns the cube and alone can offer the next redouble.

The values progress 1, 2, 4, 8, 16, 32, and 64. A gammon or backgammon is multiplied by the current cube value, so the cube can make gammon danger central to both doubling and taking.

The three questions

1. Is the position good enough to double? Consider your current advantage and whether the opponent has a live take.
2. Is it too good to double? If many wins are gammons and the opponent would pass, playing on at the current cube may be worth more.
3. Can the opponent take? Compare the cost of taking and losing with the certain cost of passing, then adjust for gammons and future cube ownership.

These questions are related but distinct. A position can be a correct double and a correct take. That window is the heart of cube play.

Market losers and volatility

A market loser is a plausible next sequence after which the opponent no longer has a take. Racing positions with a few decisive rolls and contact positions with powerful attacks can be highly volatile. When many ordinary sequences lose your market, waiting can cost more than doubling slightly early.

Quiet holding games may be less volatile. Their equity changes more gradually, so the double can often wait. The board structure matters as much as the headline winning chance.

Take points are not universal

In a money game without gammons or future cube value, the familiar break-even take point is 25 percent: passing loses one unit, while taking produces a two-unit game. Real positions include gammons, recube potential, and unequal access to future cube action, so the practical take point moves.

• More gammon losses make a take less attractive.
• Useful recube potential can make a take more attractive.
• A dead cube removes future ownership value.
• Match score can radically change both players' incentives.

Money play and match play

At a match score, the value of reaching each future score matters. A cube that is routine in money play may be wrong when gammons have little value, and a normally thin take may become mandatory when passing leaves almost no match-winning chance. At Crawford, the cube is not available for that game.

Do not transfer a cube percentage from one score to another without checking what a win, gammon, pass, and take each do to the match.