Mastering Backgammon
 How to Play the Build-or-Split Rolls by Bill Robertie This article originally appeared September 7, 2006 on Pokernews.com.

Last time we looked at the general goals that guide play in the very early game. Now we'll start to look at particular opening rolls and see how best to play them.

Note that there are only 15 possible opening rolls. The rules require each player to throw a die to start the game, and the player throwing the higher number moves first, using his die and his opponent's die as his roll.

So if I throw a 6 and you throw a 2, I move first and my roll is a 6-2. (Some players use a non-standard variation where the winner of the opening roll-off then rolls again, and uses that number as his opening roll. This variation allows doubles to come into play but it's not part of the standard rules and no tournament would permit this.)

Here's the starting position again:

 Diagram 1.The starting position.

Keep the starting position in mind as we divide the 15 opening rolls into four groups, based on common characteristics:

 The forced rolls 3-1, 4-2, 5-3, 6-1, and 6-5 (5 rolls) The build-or-split rolls 5-4, 5-2, 4-3, and 3-2 (4 rolls) The run-or-split rolls 6-4, 6-3, and 6-2 (3 rolls) The slot-or-split rolls 2-1, 4-1, and 5-1 (3 rolls)

### Playing the Forced Rolls

We called these rolls "forced" because one way of playing them dominates all the others. Here are the right plays with each of these rolls:

With 3-1, make the 5-point with 8/5 6/5. (This is the best opening roll, making the strongest inner-board point.)

With 4-2, make the 4-point with 8/4 6/4. (This is considered the second-best opening roll, just a shade better than 6-1.)

With 6-1, make the 7-point (also called the "bar point") with 13/7 8/7.

With 5-3, make the 3-point with 8/3 6/3.

With 6-5, run a back checker to the midpoint with 24/13.

Four of these rolls actually make a blocking point. While the fifth, 6-5, completely escapes a back checker. These are big accomplishments from the opening position, which is why the rolls aren't played any other way.

You may wonder why 6-1 isn't considered the "best" opening roll. Many beginners like it because it makes three points in a row, which looks like a strong blocking formation. The problem with 6-1 is that, while it makes a blocking point, it doesn't make an inner-board point. The 3-1 roll, which is better, makes both a blocking point and an inner-board point, and closing inner-board points helps keep your opponent on the bar when hits occur.

### Playing the Build-or-Split Rolls

There are four rolls in the "build-or-split" category. These are named because the main choices for each roll are either bringing two builders down from the midpoint or bringing down one builder while splitting the back men. Let's look at each roll in turn.

5-4: The building play is 13/8, 13/9, and the splitting play is 13/8, 24/20.

 Diagram 2.Position after 13/8, 13/9. Diagram 3.Position after 13/8, 24/20.

Both these plays have merit. The common part of each play is 13/8, using the five to bring down a builder and unstack the midpoint. Playing 13/9 with the four adds another useful builder while creating a huge number of rolls that now make one of the key blocking points (the 5-point, 4-point, and bar-point). Playing 24/20, on the other hand, starts the crucial 20-point anchor, while guarding White's outfield and preventing White from conveniently bringing down builders of his own.

What's the right play? Master opinion considers the two plays very close, but most top players prefer splitting with 24/20 in money games or matches where the score is close. The 20-point is very important, and splitting is the most direct way to fight for it. Of course, Black's 5-point is also crucial, but 13/9 only creates a few more rolls that directly make the 5-point.

One note: if you're trailing towards the end of a match, so that winning a gammon gains a lot and losing a gammon is not so costly, then 13/9 is clearly right. The extra builder restrains White from splitting his back men (because you have more ways to attack) and more gammons result when your opponent isn't able to make an advanced anchor quickly.

5-2: The building play is 13/8, 13/11, and the splitting play is 13/8, 24/22.

 Diagram 4.Position after 13/8, 13/11. Diagram 5.Position after 13/8, 24/22.

The situation here is obviously similar to the previous play; 13/11 adds a builder, while 24/22 splits to a potential anchor point.

In this case, master opinion heavily favors the split play. While the 22-point is apparently only a modest improvement over the 24-point, it's enough to reduce the gammon danger significantly when Black makes it. In addition, the split back men give plenty of extra coverage over White's outer board.

Playing 13/11, on the other hand, doesn't add a lot of new building numbers to Black's arsenal. He gains 4-1, 6-4, and 6-3 to make new blocking points. That's not nearly as big a gain as after 13/9 with a four.

Next time:  How to play the 4-3 and 3-2 rolls.