From my previous post:
D (Down, 13/10* 13/9) is a bad play because it strips the midpoint. That leaves X (hit-and-split, 24/20 13/10*) and @ (anchor, 24/20 23/20) from which to reasonably choose. Which is better?
To deduce the answer, look at the front jacket cover of Backgammon Openings (either on the book itself, or click here and scroll down). Does that ring a bell? If not, turn to page 44, where the three best candidate plays are shown on the right-hand side of the page. Then look again at the position here (51S-63R-43). Which is better, X or @?
For those who might not have grasped the connection and/or don't have Backgammon Openings, page 44 is laid out as shown below. The problem position is in the upper left corner of the page. The candidate plays, in order of strength, are diagrammed down the right side of the page.
------------------------------------------------------------------------------------------------------------------------ The fourth right-side diagram isn't actually on the page, but you can infer by its absence that the three plays above it are stronger. In this case, it happens that the equities of plays shown in the second, third and fourth diagrams are all very close together (by Snowie rollout in a range of about .012; by XG rollout evidently in a range of only .006), but here is the point:
If the fourth way to play the 31 (hit and split) is inferior to the second way of playing 31 (anchoring), then it follows that: in the first position of this post (which is the feature position of Neil's thread), hit-and-split with 43 (i.e., 13/10* 24/20) is inferior to anchoring (i.e., 24/20 23/20) with 43. The positions after moving those two pairs of candidate plays are identical.
Nack
