Bill Robertie’s Blog

Bill Robertie welcomes the opportunity to share his knowledge of backgammon with experienced players and beginners alike.

On his blog, Robertie publishes set and equipment reviews, creates quiz contests and provides free lessons. He would be remiss not to include his Robertie’s Rules! He also educates readers of the Gammon Press blog on the history of the game, offers backgammon instruction and more.

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A Back Game with Questionable Timing

Dec 15, 2022 | Backgammon Problems: Back Games

Cash game. White owns the cube. White on move.

White to play 4-3.

This isn’t a particularly hard position when presented as a problem. The right play is 8/5 13/9, keeping both back points, slotting the 5-point, and playing 13/9 so as to create two cover numbers for the 5-point.

Over the board, with no one hinting that this is actually an interesting position, it’s fairly easy to make a small mistake. I’d expect to see a lot of players move either 13/9 13/10, a slight error because it doesn’t start the 5-point, or 8/4 8/5, another slight error because the builder on the 4-point is somewhat misplaced and White has fewer cover numbers for the 5-point than he should.

Leaving a blot on the midpoint after 13/9 8/5 is not especially costly because for the most part Black doesn’t want to hit it. Let’s take a quick look at how Black should play his aces after White plays 13/9 8/5.

Black needs to notice these features of the position:

> If he can play safe and not hit, he should do so. Not hitting leaves White’s timing in jeopardy, while hitting improves White’s timing somewhat and may give White a shot at Black’s blot on his ace-point. Right now White trails by 65 pips in the race, which is enough to give him some reasonable winning chances, but not enough to say that he has a well-timed back game. One extra checker back, especially if White could dance for a turn, would make a big difference.

> Playing safe is essential for Black, so if he can only play safe by hitting, he will do so. Black very much doesn’t want to get hit right now, because White’s board is already strong enough to cause real trouble.

> If Black can’t play safe, hitting wins more gammons, and may decrease the count of hit and cover numbers.

So with 6-1, 5-1, and 4-1, the best plays are 13/6, 13/7, and 13/8, all without hitting.

With 3-1, Black can only play safe by hitting, so the right play is 13/12* 4/1.

With 2-1, Black can’t be safe no matter how he plays, so he should hit. Hitting substantially increases his gammon chances compared to the non-hit play (13/11/10), while his losing chances are close after both plays.

As a last point, note that White shouldn’t consider playing 23/16 with his 4-3. While it’s true that his back game/holding game isn’t ideal, it’s the only game he has. Playing 23/16 breaks much of the contact and leaves him 58 pips behind in a game that will mostly become a 5-point holding game, an essentially hopeless situation. If White really wanted to break one of his anchors, the better choice is to keep the back anchor and play 20/13.

Priming Games: Escape or Build Structure?

Dec 1, 2022 | Backgammon Problems: Priming Games

Cash game. Center cube. White on move.

(A) White to play 6-1.

(B) White to play 6-1.

One of the most difficult choices in the early and middle stages of a backgammon game is the choice between creating structure (a blocking prime) and attending to issues on the other side of the board. Those issues vary: you might be able to hit a checker, or make a defensive anchor, or escape one of your back men. In some cases, making structure is correct. In other cases, playing on the other side of the board is correct. Let’s take a look at a couple of examples, to see the ideas that have to guide us in these decisions.

Let’s start with Position (A). It’s not a tough problem. White can hit a blot with 24/17* or build some structure with 13/7 8/7. The structural play has two problems: the structure isn’t that impressive, and it gives Black a direct shot at White’s blot on the 14-point. For structure to trump hitting, you want structure which is solid and imposing.

24/17* might look loose, but it accomplishes two great things: hitting an important blot, and escaping a rear checker. True, Black may hit back. He has a total of 16 return hits (all twos except 2-6, and all fives except 5-6). But that leaves 20 rolls that don’t hit, and those are great rolls for White – he’s ahead in the race and his rear checkers are out. Potentially getting all your back checkers out is a great result, and 24/17* puts White within striking distance of that goal.

Problem (B) occurs much later in the game. White has two choices: he can block in Black’s two rear checkers with 13/7 8/7, or he can escape his own last checker with 24/17. Running out is more volatile – if White gets away with it, he’s close to a double, but if Black hits, White is an immediate underdog. Making the 7-point, on the other hand, leaves White a solid but unspectacular favorite in most variations.

What’s right? White should go ahead and make his 7-point. There are two reasons:

(1) With an advantage and a centered cube, you’re not looking to make big swing plays. You’re more interested in plays that preserve your advantage and creep closer to an eventual good double. When in doubt between the merits of two plays, lean to the more conservative choice.

(2) Trapping two men will increase your gammon chances dramatically. There’s actually not much difference in raw winning chances between the two plays, but locking in Black’s two back checkers will win many more gammons.

The basic idea in these positions is a simple one: the quality of the structure you build is crucial. Turning a very weak structure into a slightly better structure, as in Position (A), isn’t worth that much. Turning a broken structure into a 5-point prime, as in Position (B), is huge, even when the alternative is escaping the last checker from behind a 5-prime! The lesson to be learned is that creating a 5-prime or even a 4-prime may outweigh making progress on the other side of the board, but just building a blocking point or a 3-prime is probably not enough.

Holding Game Doubles

Nov 15, 2022 | Backgammon Problems: Holding Game

Cash game. Center cube. White on move.

Should White double? If he doubles, should Black take or drop?

Here’s an interesting cube position. Black has an anchor on White’s 5-point. White’s ahead in the race by 21 pips, 117-138. White also has a pretty good 4-point board. Black’s remaining checkers are in play and his board is in the process of forming.

Two Middle Game Doubles

Nov 1, 2022 | Backgammon Problems: Middle Game

Cash game. Center cube. White on move.

(a) Should White double? If he doubles, should Black take or drop?

(b) Should White double? If he doubles, should Black take or drop?

These two positions show a couple of very typical middle game doubles. In each case we’re six to eight moves into the game, one side has finally grabbed a noticeable advantage, and now they’re thinking about turning the cube. Double? Take? What’s right?

Let’s start with the doubling question. The best general guide to early/middle game doubles of this sort came years ago from Joe Sylvester. (Joe was one of the titans of backgammon in the 1980s and 1990s, and he won the first World Cup in 1988. Today he’s somewhat inactive.) Joe recommended looking at three features of the position: the race, the structure, and threats. His rule was the following: if you have an edge in at least two of these three, then you have a double.

With this idea in mind, how’s White doing in Position (a)?

> White leads in the race, 133 to 149, a 16-pip lead.

> White has a better structure, with a 4-point block, his 4, 5, and 6-points already made, and good distribution. Black lacks his 4-point and 5-point and has a big stack on his 6-point.

> White has plenty of immediate threats. Twos hit the blot in Black’s board, 6-1, 6-3, and 3-1 make a 5-point prime, and 6-4 points on the 2-point. White’s edge is threatening to get much bigger next turn.

With an edge in every department, Sylvester’s rule suggests White should have a strong double in Position (a), and in fact he does.

Now let’s look at Position (b).

> White leads in the race, 134 to 162, a 28-pip lead.

> White has a better structure, with four points made in front of Black’s anchor. In addition, Black has three men back on his 23-point, which is weak. Black also has no inner board yet, which is also weak. Here the issue is not so much that White is strong, but that Black’s pretty weak.

> White has no particular threats. True, 6-1 makes his 5-point, and a few numbers will run his back checker into the outfield. But that’s more the sort of background threat noise that’s present in every position.

Here, we can say that White has an edge in two out of the three criteria. Again, he has a solid double.

Now, what about the take/drop question? Here I’ve got my own rule. I ask myself three quick questions. If the answer to the first and third questions is ‘yes’, and the answer to the second question is ‘no’ I’m pretty sure I’ve got a take. If not, then I’ll look at the position more closely. My questions are:

> Do I have an anchor?

> Does my opponent have a 5-prime?

> Is there still contact on both sides of the board?

Take a look at Problem 1 and Problem 2. In both cases Black has an anchor, in both cases White hasn’t yet built a 5-prime, and in both cases we still have contact on the other side. With all these conditions in place, it’s hard (although not impossible) for Black to be a 3-to-1 underdog in the game. In both positions, Black’s best guess should be that he probably has a take. And in fact, rollouts show that’s the correct action.