Diversification

Diversification is the mirror image of duplication. When you duplicate, you arrange your checkers so that your opponent's good numbers overlap and fewer of his rolls work for him. When you diversify, you arrange your own checkers so that as many different numbers as possible will be useful to you on your next turn.

The idea is simple: every roll of the dice is a lottery, but you decide how many winning tickets you hold. If only sixes help you, you have a little under a third of the rolls on your side. If sixes, fives, twos and ones all help, nearly every roll does something good.

A typical middle-game example

Picture a middle-game position where the race is roughly even and Black has a checker on the bar. Both sides have made a few points, and neither has taken control yet. White rolls 5-4, a roll that can tip the game in his favor if he plays it well.

The four is easy. White plays 8/4 and makes his 4-point. That adds another closed point in front of the checker on the bar, so Black will find it harder to enter, and Black can no longer hit anything when he does come in. The real question is the five.

Candidate plays for the five

• 23/18. This prepares to make the 18-point next turn, but it leaves a direct shot. Black would hit with sixes, fours and ones, and the chance that he misses all of them is small. It is an interesting play from a duplication point of view, since several of Black's hitting numbers would also be the numbers he wants for other jobs, but it is not the best move here.
• 13/8. Bringing a checker down from the midpoint is completely safe, but it achieves very little. It is a passive move in a position that calls for action.
• 20/15. Running a back checker toward the midpoint is not constructive either, and it gives Black several ways to hit.
• 11/6. This puts a third checker on the 6-point. It is the strongest play.

Why 11/6 is the diversifying move

After 8/4 11/6, White has an extra checker on his 6-point that can be used to attack. Before the move, White needed one particular number to hit a checker that comes in from the bar. With the spare on the 6-point, plus the new 4-point and his other builders, White now has many different numbers that hit an entering checker. If Black comes in on White's 1-point or 2-point, White can hit with a wide range of rolls, and only a few of Black's own rolls avoid leaving him exposed to a strong attack.

That is diversification at work. White did not try to guess which number he would roll next. He placed his checkers so that almost any number would be useful. In practice this often means:

• keeping builders at different distances from the points you want to make;
• avoiding stacking several checkers where they all need the same number;
• placing spares so that they aim at different targets, such as an entering checker on the 1-point and another on the 2-point.

This is exactly the thinking behind a blitz: the attacker wants as many hitting and point-making numbers as possible while the opponent is on the bar.

Diversification and duplication together

The two ideas often appear in the same move. A good play can diversify your own numbers while duplicating your opponent's. Strong players look at both sides of the board before they move: which of my rolls will be good next turn, and which of his rolls will hurt me?

Conclusion

Diversification, like duplication, is a way of staying in charge of the game. Still, the dice decide each turn, so you cannot play every move only to diversify. Keep the idea in mind without making it the only thing you think about. With experience you will start to notice positions where spreading your builders gives you extra good rolls, and the habit will become a natural part of your backgammon strategy.