Duplication

You can play backgammon safe, but that’ll get you nowhere in the long run. To be a winner you need to take risks, something that can’t be emphasized enough. You can, however, take risks either by minimizing them or by being a total fool and not thinking at all. Duplication is the tool you need understand to achieve the first one. There are differing opinions as to how much focus should there be on duplication in backgammon, such as noted in this posting on duplication in Backgammon Galore. We believe that when used correctly you don’t need to focus on duplication as such but that it will become an essential part of your backgammon.

What is duplication

One of the most difficult backgammon concepts for beginners to grasp fully is duplication. It’s not a concrete strategy you can follow or strive for like priming games and the Blitz, but rather a strategical element of your game. No doubt you will need some experience before you start seeing how to use it effectively and make the right decisions within seconds, but we’ll help you out.

So what is duplication? In short, it is a strategical element of your game whereby you try to limit the number of good rolls for you opponent. Say, your opponent has a chance of hitting one of your blots but at the same time he could also use the same roll to cover one of his own. That’s duplication - forcing your opponent to a compromise decision.

Duplication examples

To better understand duplication in practice let’s look at a couple of situations where it can be used.

Voluntary shots

In diagram 1 white has rolled 4-2. Because the 21-point is taken he needs to enter from the bar with the two, b/23. So what would you normally do with the four? The safest move would be moving a checker from the 8-point to the 4-point leaving no direct shot. You could move the back man from the 24-point to the 20-point in hoping to make the 20-point next round or to try to escape it. Duplication helps us understand why both are wrong moves and that the correct play is 13/9 although it leaves a direct shot.

Diagram 1: White has rolled 4-2.

Let’s examine the board. If White moves a man to the 9-point Black will be able to hit it with a four. That’s a whopping 42% chance! But what is more important fir him at this stage? Hitting or making the 5-point? Because Black needs also a four to make the 5-point and he can do only either one with a four, assuming that he’ll roll one or a combination of four. At this stage the pip count is pretty even but the White has already made three home board points and is heading strongly for priming game. So yes, you guessed right: Black will be surely tempted to hit the White’s blot on the 9-point but it is much wiser of him to make the 5-point. This in turn will give White a great chance to make either the 9-point or 7-point next round.

Forced shots

In the previous situation White could’ve played safe but he chose to leave a direct shot. However, what if you simply don’t have a choice and you have to leave a shot? Duplication again proves very useful.

Let’s look at diagram 2. With a big roll White will be a definite favorite to win the game by moving his man on the 18-point over Black’s firm 12-point, but no - he rolled 2-1 and the f-word. Common sense would dictate that now he’d move the checker as close to the 12-point as possible to minimize the chances of being hit, but duplication gives us the answer to the correct move again: 18/17 and 4/2. Why? First, let’s analyze the current short-term objectives for both players.

Diagram 2: White has rolled 2-1.

White desperately needs to run his lonely guy to safety, simple as that. Black on the other hand needs to a) prevent white reaching his objective and b) cover the blot on his ace-point. Quite surprisingly, the second objective is more important than the first one. See, if Black hits White’s checker before he makes his ace-point, White might enter the board on the 24-point on his next turn and send the Black’s checker to the bar. If that happens, looking at White’s five-prime, Black could almost just as well resign - chances are that white will build a six-prime and take it all away in a matter of few turns. So, keepin all of this in mind, let’s examine the two discussed moves again: 18/15 and 18/17 4/2.

Option 1 - 18/15
If White moves the checker to the 15-point Black has three good rolls he can use: 3-3, 3-5 and 5-3. With 3-3 he can hit and make the 15-point and the 22-point. 3-5 and 5-3 would be ideal rolls for him, he could both hit the White’s checker with the three and make his ace point with the five. White would then be a real underdog in the game.

Option 2 - 18/17 4/2
With this move White puts duplication to use, reducing the number of good rolls for Black to only one: 5-5. That’s the only roll that would allow him to both hit the checker and make his 24-point. Should he roll e.g. 5-3 he should rather make his 24-point than hit, giving white an excellent chance to run his checker to safety and win the game.

Conclusion

As we said in the beginning of this article, it’ll take a few games before you will start noticing when and where duplication can be used. It’ll then take a few more games before you’ll be making the right calls, but at this stage you don’t have to worry about too much - it’ll come naturally later. Just keep duplication in mind and practice it whenever you can.