Prime vs. Prime

In this blog post, we're going to look at a specific type of position we call "prime versus prime" or a "priming battle." Look at the position below:

A "prime versus prime" position typically occurs in the middle game because both players still have back checkers, meaning neither has achieved full freedom. A key characteristic of this position is that both players are aiming for a priming strategy. In the image above, White has formed a prime trapping two of Black's checkers, and Black has also formed a prime trapping two of White's checkers.

The first thing that matters in a prime versus prime is the structure: Whoever has the stronger structure has an advantage. Let's look at the structure in this case (same as the picture above).

White has a solid five-prime, as does Black, creating a symmetrical structure. However, the effectiveness of their priming differs.

Black’s five-prime blocks White’s anchor, which sits on the edge of the prime. These edge checkers have an escape route; they can jump out with a roll of six. In contrast, Blacks’s two trapped checkers within White’s five-prime lack a direct escape route in a single move. Consequently, these checkers are more effectively primed than Whites’s anchor, giving White a significant advantage.

Another crucial element in a prime versus prime scenario is timing. Timing refers to the game's flow and indicates the strength of your position leading up to the critical moment. (see also; our blog post about timing)

In a prime versus prime, the critical moment usually occurs when one player involuntarily breaks their prime. The player forced to break their prime first will likely lose. Therefore, better timing allows you to maintain your structure longer, while poor timing means your position will collapse sooner.

Let's revisit the same position:

White possesses significantly better timing than Black because White has a good supply of spare checkers on the midpoint. These can be moved forward with a few rolls to maintain the prime's structure.

In contrast, Black has only one spare checker on their five-point. This illustrates that being ahead in the race in this prime versus prime scenario is actually a disadvantage in terms of timing. Generally, in a prime versus prime, superior timing is desirable, making it often advantageous to be behind in the race – the opposite of typical backgammon strategy.

Furthermore, Black's two checkers trapped behind White's anchor are detrimental to Black's position as they currently serve no useful purpose. Ideally, Black would prefer these checkers to be positioned to form a six-prime.

Or even less advanced to gain more timing. If those checkers were positioned further up, Black could make several more moves before being forced to break their five-prime. However, as the position stands, Black will likely have to break their prime on the next turn, allowing White to escape while keeping Black trapped. Black being forced to break their prime would be the critical turning point in this prime versus prime game.

For example:

Even with a remaining four-prime, the situation is significantly worse for Black. Losing a point from the prime drastically reduces its effectiveness and allows White an easier escape. Now, both rolls of five and six will enable White to jump over the remaining prime. At this stage, the priming battle is essentially lost for Black. White should likely offer a double, which Black would be in a poor position to accept.

Consider a scenario where White has slightly better timing, as illustrated below:

In this scenario, Black possesses sufficient timing to confidently accept the doubling cube.

Let's also consider a slight improvement to White's position. In priming battles, moving pips backward can often enhance timing. For instance, the following position is even more advantageous for White, despite a loss of three pips:

Regarding the open checker there, we should refer to it as a slot because it's being placed strategically, like "slotting" on a slot machine, to achieve our desired outcome. In this instance, White is slotting to create a six-prime – the most powerful structure in backgammon. So, we've discussed structure.

Before we conclude, let's define a strong structure. What constitutes one?

A strong structure is a pure structure, meaning it has no gaps. Additionally, it's an efficient structure, one that maximizes the utilization of your checkers. For example, the following structure is highly efficient:

You've got eleven checkers. Ten of them form the five-prime, and one is a useful spare checker – that's efficient. So, purity and efficiency are definitely very important aspects of a strong structure.

In summary, the two key elements for navigating a prime versus prime position (also known as a priming battle) are:

• Maintaining good timing (which often means being behind in the race).

• Establishing a superior structure.

See you in the next blog post, and good luck in your games!

You can see the full video here!