A Time to Block, a Time to Race
Paul Magriel, 1977
New York Times, August 11, 1977
Backgammon is in part a blocking game and in part a racing game. In many positions, however, one strategy may predominate. Distinguishing between these two strategies and selecting the appropriate one is essential.

Black to play 4-2.

In the diagrammed position, Black placed himself in unnecessary peril by failing to make the proper distinction. When he rolled 4-2, he played 14/10, 12/10, making his own 10-point. With this move, Black was following an important rule for blocking: When your opponent has a point in your inner board, the most effective point for you to hold is five or six pips in front of him.

Black’s judgment, however, was seriously in error. A blocking strategy is inappropriate for this position. As the diagram shows, Black is far ahead in pips, and his sole objective now should be to win the race. He has no need to contain White on the 5-point, so owning the 10-point is not an asset.

To win the race, Black needs to bring all his men home safely. Black’s move, which doesn’t leave any blots on the board, appears safe — but only on the next roll. Later in the game, the 10-point could become a serious liability. If White reenters, then White will be holding Black, not vice versa. Black may have difficulty moving his men off the 10-point without giving White a direct shot; less than one third of Black’s possible rolls will enable him to move both men off the 10-point without leaving a man exposed.

(a) 14/10, 12/10
(b) 12/6
The correct play is 12/6. By not making the 10-point, Black could avoid difficulties later. With this play, he would only have to bring his last remaining man on the 14-point home for an easy victory.

In the actual game, Black was given a chance to undo his first mistake — making the 10-point. White stayed out and Black rolled a 3-1. He played 6/2, again to avoid leaving blots. This play further compounded his error. With White still on the bar, Black missed a fine opportunity to break the 10-point by playing 10/6. Although White could now reenter and hit with 5-5 (one chance in 36), this small risk was justified.

Black paid dearly for his mistakes. White reentered next roll and Black realized too late that his two men on the 10-point were stranded. A few rolls later, Black was hit trying to clear this point. White won easily.

XG logo
Tom Keith 2013 
Money play
White owns 2-cube
Black rolls 4-2

1296 games with VR
Checker play: 2-ply
Cube play: 3-ply Red

4-2: Game BG   Equity
1 12/6 W
+1.0146 x  (b)
2 14/10, 6/4 W
+0.9607 (0.0539) 
3 14/8 W
+0.9592 (0.0554) 
4 14/10, 12/10 W
+0.9417 (0.0729)  (a)

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