||Black to play 6-1.|
As I analyze it, her half-move 24/18 (Diagram A) gives up the one-point anchor prematurely, duplicates her own 3's, doesn't fight for her five point — the number one priority here — and gives her opponent too much flexibility. Her opponent, if he enters (an 8-to-1 favorite to do so), will hit on the five point (with a 5 or 4), the eighteen point (with a 1, 3, or 6), and with double 2 on the five point.
The other play, 13/7 (Diagram B), maintains the defensive one point and forces the opponent to throw a 4, 5, or 6. All other plays, except double 6's, are giving Black a wonderful opportunity to establish a strong block. In addition, in a hitting contest, he has that possible 2 to fight for the five point. On the other hand, 5-2, 2-5, and double 2 are much better for her opponent now. However, on balance I still prefer building than splitting.
Unfortunately, the authors do not discuss the merits of either play, the relative strength of the opponent, or the psychological pressure this early in a match (such as Barclay Cook did in Championship Backgammon and I am left a little lost . . . what did I miss?
Bob's question in their article:
The First Step in Learning