A commonly occurring cube decision appears after an opening blitz, where one player splits his back checkers, and his opponent rolls a doublet that both makes inner board points and hits a checker, like a 55. We have already discussed these types of positions in previous lessons, and as promised, we are finally going to study them in greater detail today!
We are going to go over a series of common reference positions and will discuss their cube actions and the plan is…. to just memorize them. Sure, they appear frequently enough that this will be a useful exercise, but the real value will come from being able to compare to these specific positions when at different stages of real games.
All of these positions start the same way — Gary splits his backcheckers, you roll a doublet that puts one or both of them on the bar, and then Gary fans, entering 0 or 1 of his checkers. As we will see, the location of the entering checker can make a significant difference to the cube decisions for both players. We will look at 55s, 44s, and 33s for unlimited games. We will discuss how the match score affects the cube actions for some of these positions in a later section.
Double 5 blitz
A blitz initiated with a 55 is a real commitment to playing a blitzing game. You’ve made the ace-pt and the 3-pt, and so all of your inner-board points are very deep, meaning that you have thrown the priming game plan out of the window. For this reason, the cube action for both players is highly dependent on how well you can execute a blitz, which turns out to be highly sensitive to the location of the second backchecker.
A blot on the 7-pt
The first position has 1 checker on the bar and a blot on the 7-pt. This is the worst-case scenario for Gary, since not only will it be easy for you to continue the blitz with many hitting numbers, but you can do so at no risk to yourself, whilst also bringing in more ammunition from the midpoint. This is a clear D/P.
2 checkers on the bar
If the mere prospect of a second checker ending up on the bar makes the previous position a pass, then it should naturally follow that having both checkers on the bar is an even clearer pass.
This is another clear D/P.
A blot on the 2-pt
At the other end of the spectrum, Gary might enter a single checker deep on the 2-pt:
That little guy is tucked away quite nicely. If you want to continue the blitz attack, you might need to hit it loose, and then struggle to cover it with only a single covering number (from the 6-pt)… and you really don’t want to make the ace- 2- and 3-pts, anyway, because it leads to an inflexible anti-priming gaming plan, and if your blitz fails, you are out of options. If you hit loose and fail to cover the 2-pt, and Gary enters and hits you there, the checkers from the midpoint (“the backup”) will have to travel a long way, at which point you’re also out of ammunition with only 7 checkers in the zone. I hope you can tell by my tone how unfavourable this situation is. All of these elements add up to a ND.
A blot on the 5-pt or 4-pt
With the positions at the extremes out of the way, we are left with the sweet spot — a blot on either the 5-pt or the 4-pt:
Both of these positions are D/T, although based on the discussion above, it should be clear that white would prefer to enter on the 4-pt than the 5-pt.
Double 5 blitz summary
To summarize, for double 5 blitz:
- 2 checkers on the bar: D/P
- Blot on the 7-pt: D/P
- Blot on the 5-pt or 4-pt: D/T
- Blot on the 2-pt: ND
- No checkers on the bar: ND
Double 4 blitz
Compared to a 55 blitz, a 44 blitz is much more balanced. If the dice don’t cooperate, you could easily abandon the blitz attack entirely and transition to a priming game. On the other hand, Gary will always have a lone blot on the ace-point, which we now know from the discussion above acts as a major asset for his position. Let’s see which of these two competing factors wins out.
1 checker on the bar
Whereas in the 55 blitz, having 1 deep (safe!) checker with another on the bar is a clear No double, here there is still enough to double. The alternative priming game plan adds just enough flexibility. Gary also has a comfortable take, so combined it’s a D/T.
Given that in every other situation, Gary will be entering that second checker, you can infer that all of the other positions will certainly be Takes for him as well. But should you double?
0 checkers on the bar
No, the answer is no:
In both of the positions above, you simply don’t have enough to double. These are both ND positions. If white anchors on the ace point, the blitz game plan is nullified completely, and it too is an ND. Simply put, if there are no checkers on the bar, do not double.
Double 4 blitz summary
- 1 checker on the bar: D/T
- 0 checkers on the bar: No double
Double 3 blitz
The double 3 blitz is very similar to the double 4 blitz in that Gary’s checker will be on a deep point, and that you will have alternative game plans to pursue if the blitz fails. Therefore, it should come as no surprise that the cube actions are very similar, as well:
1 checker on the bar
Just as it was for the 44 blitz, 1 checker on the bar is enough for you to double, but not too overwhelming for Gary. This is a D/T.
0 checkers on the bar
Also like the 44 blitz, with no checkers on the bar, you should not double. Both of these positions are ND positions.
Double 3 blitz summary
- 1 checker on the bar: D/T
- 0 checkers on the bar: No double
It’s worth memorizing these positions, and experimenting with them using the bot of your choice. It’s surprising how much having 1 extra or 1 fewer checker in the zone can completely change the cube action. The resources below shed a bit of light on the extra considerations to have in mind in these sorts of situations.
Further reading:
- A video by Dan Rovira on the Backgammon is Beautiful channel.
- A similar video by Justin Nowell that also discusses these reference positions.
- The reference book Backgammon Encyclopedia vol. 1 by Kit Woolsey, which you can purchase on Justin’s website. It contains detailed rollouts for these positions and many more.
Next lesson: Doubling in closeout positions
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