What are Magriel’s Criteria?
In Chapter 16 of his classic Backgammon, Paul Magriel outlines several features of positions which should incline you towards bold plays:
- An advanced anchor (on the 20 or 21 point).
- More inside points than your opponent.
- A blot in your opponent’s home board (which offers return shots from the bar if you get hit).
- More checkers back than your opponent.
Conversely, the absence of these features should incline you towards safe plays.
||Black to play 4-3.|
Several features of this position call for a bold play:
- Black has four inside points against white’s two.
- Black has the strong golden anchor (white’s five point) as an assured reentry point if hit.
- Black has three checkers back to white’s one.
- White has a vulnerable blot on his three point.
Instead of the passive 15/11, 8/5, which poses only a minimal threat to white’s last checker if it can leap out to the outfield, black does well to play 20/16, 8/5. Now White’s last checker can be hit with 5’s or 2’s if it stays, or many different rolls if it escapes.
Though white may hit black on the 15 or 16 point, white has a stripped position and will leave many return shots. Remember, an exchange of hits favors the side with more men back and the better board.
||Black to play a 2.|
Here, the bold play of 6/4, slotting the four point, would be wrong. Magriel’s criteria (fewer inside points, no anchor) suggest playing safely. 8/6 (keeping the active builder on the seven point and leaving only an indirect shot), or 7/5 (keeping the four-prime) is better.
||Black to play 6-1.|
Again we see a position suitable for a bold play. Black has two men back while white has none and has the better board as well (two inside points to white’s one). Black should move 24/18 with the 6, creating contact and encouraging an exchange of hits rather than playing passively and letting white build points unmolested.
With the ace, black should move 10/9. (5/4 is also possible, but it is unwise to slot an inside point voluntarily when initiating a blot hitting contest — to do so offers your opponent a new target for the bar and sometimes lets him hit two checkers.)
Magriel calls this an action play. Black expects to get hit but threatens to hit back . . . or to hit white’s outfield blots if white doesn’t hit.
Most action plays occur when an opponent has escaped with both back checkers. If white still had a man back, black would do better just to make his four point, 10/4, 5/4.