Using reference positions

Having studied a variety of cube positions (such as holding games, blitz games, or n-roll positions) gives us clear cube action instructions for a set of well-defined situations. We can use these positions as reference positions to dramatically expand the domain in which our newfound cube judgement may apply. Though we’ve discussed this concept briefly in previous articles, it’s worth dwelling on a bit now that we have the appropriate background to appreciate it.

Consider this position below:

This looks like a double 3 blitz that we discussed in our article on blitz cubes. However, when comparing directly to that position, we notice that our position has a meaningful improvement: instead of only having the 8 starting checkers in the zone, we now have 10. This contributes enough to our standing that the right cube action blows past the D/T from the previous position into pass territory.

This “position adjustment” analysis can actually go both ways. The position below also resembles the double 3 blitz, but with a different adjustment:

Here, before we attempted our blitz, Gary was able to make his 5-pt. He’s still got a checker on the bar with a loose blot in his home board, and we still have a 3-pt board, but despite these threats, his position is meaningfully stronger. This change is sufficient to prevent us from offering a double! The current cube action here is No double / take.

Most positions encountered in a real match will differ more significantly from the references than what we have illustrated here. However, we can still accurately determine the cube action for a variety of positions using a simple tally scheme: we compare all the different features of the position to a known reference, adding 1 to the tally for each improvement to our position, and subtracting 1 for each improvement to Gary’s. The final tally measures roughly how different a position’s strength is when compared to a reference. If the net tally is 0, we have the same cube action as our reference! If the number’s large and positive, it’s probably a pass; if it’s large and negative, then it’s not a double.

In the position above, we included both of the adjustments we’ve discussed in this article: we have 10 checkers in the zone, but Gary has his 5-pt. Combined, your tally balances out, meaning we have recovered the Double/Take cube action from the reference position.

Finally, we present an example of the tally system at work in a holding game position:

We know that we should not consider cubing in a holding game until we have 4 or fewer checkers remaining on our midpoint. Having 5 checkers, as we have here, is a weakness to our position. However, Gary hasn’t managed to anchor up his backcheckers yet. He has a weakness as well! The two weaknesses roughly cancel out, therefore matching the reference, resulting in a Double/Take.

Next lesson: Score-based cube actions