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Here we see three closely related positions. In each case, Black will enter with his three, hitting, after which he has to decide on the best play for his six. He can run out of White’s board (with either 22/16 or 21/15) or he can hit in his inner board with 9/3*, breaking his 9-point in the process. What we want to know is how, if at all, Black’s structure affects his choice of plays.
When studying backgammon, many players make the mistake of examining only isolated positions. They play a practice match against the bot of their choice, then ask the bot to analyze the match, looking for errors. A certain play gets flagged as a serious error. It’s a position where they had a choice between two plays; the choice seemed hard, but eventually they picked one. The bot says they should have picked the other one. They look at the position for a few moments, trying to remember it for future reference, and then move on.
The problem with this method is that it doesn’t teach as much as you think it does. It’s all well and good to know that in such-and-such a position, play so-and-so was right, but even if you could remember that factoid, the position and roll may never recur in your games. What you really want is some insight that goes beyond the specifics of position such-and-such. A better approach is to use the puzzling position as a starting point, then generate some variations by moving the pieces around a bit. Give one side an extra home board point and see what happens. If one side has a stack, unstack the checkers and create a new point somewhere. Sometimes small changes will have no effect on the outcome, while for other positions, small changes will have a big effect. Either way, you’ll start to get a feel for the factors that really determine the correct plays.
Now let’s take a closer look at these three positions. Before we discuss the hit/no hit question, let’s settle the issue of which six Black should play if he elects not to hit. Pretty clearly, it’s going to be 22/16, because the 16-point is within direct range of the 21-point. A checker on the 16-point can be directly covered next turn with a five or a two, while a checker on the 15-point can only be directly covered with a three. So 22/16 is going to dominate 21/15.
Now let’s move to the hit/no hit question. Clearly, the most favorable position for hitting twice is (a). Black’s strong inner board makes a potential attack more powerful, while winning the battle for the 3-point would reduce White to just an ace-point game. The cube also plays a role here. If Black hits twice and White fans, it’s a double and a huge pass. If Black hits twice and White enters one checker on the ace-point or deuce-point, it’s a good double and a take. To hold off the cube, White has to enter with a three, hitting, or enter both men with a 2-1. Black’s strong potential cube action next turn makes the double-hit with Bar/22* 9/3* clearly right.
The least-favorable position for hitting twice is (b). Here Black lacks a strong home board, and his little structure with the 8-point and 9-point made is really all he has. Breaking the 9-point to hit now risks a lot to gain a little. In the very best case, where White fans, Black has a marginal double/no double decision and White has a huge take, even with two men on the bar. Entering even a single checker somewhere is enough for White to hold off the double. Now the double-hit is a clear error and the simple 22/16 is correct.
Problem (c) is trickier. We’ve moved just one Black checker from White’s bar-point to Black’s bar-point. Normally reassigning a single checker would make only a small difference in the evaluation. But here the new checker actually plays a dual role. It helps Black’s attack by being a new builder. But it also hurts Black’s defense by being a new blot. Now if Black plays 22/16, White has a ton of hits from the bar. (Note that White has perfect diversification: his hitting numbers, fours and sixes, are the numbers he can’t use to enter.) So hitting with 9/3* functions for both attack and defense, and becomes the best play by a clear margin. In fact, the runner-up is now the other double-hit number, 7/1*.
Keep in mind that in most early and middle game positions, double-hitting will be the default play. The positions here are a little unusual in that Black has four or five checkers in White’s board, which make Black’s attacking chances less effective. Position (b) is an especially good one to remember, in that it shows when switching to a plan of preserving structure starts to dominate the obvious attacking idea.
