Annotated Game

Test Your Backgammon
Paul Magriel vs. Bill Robertie

 
Bill Robertie, 1982

From Backgammon Times, Volume 2, Number 3, Summer 1982.

How often have you complained that you could play as well as the famous players, if only you could get their positions and great rolls? Well, here's your chance to prove your point. Imagine that you are sitting at the right hand of a famous master as he plays a tense tournament game. You are playing Black. Use a sheet of paper to uncover just enough of the text to reveal your opponent's move and your next dice roll. (A string of asterisks indicates when to stop.)

Try to guess his next play. Then uncover the actual play and the explanantion that follows, and score yourself. Note that partial credit may be given for plausible plays that were not chosen. Keep a running total of your score. A scoring guide is provided at the end. Good luck!

Incidentally, this game is taken from a match between Paul Magriel (Black) and this writer (White) in 1978. Black led 5–2 in a 7-point match.

  Magriel (Black) Robertie (White)

1.     4-3: 24/20, 13/10
2.     5-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 5-3.

*   *   *   *   *

6/1*, 8/5*

2 points. Once thought to be the advanced play, this move has fewer and fewer adherents as the years go by. Black hits two blots, maximizing his chance of making the 5-point next turn. Unfortunately, the cost is high. Black leaves two blots instead of one, and the blot on the ace-point, if not hit, will be a permanent liability in middle-game maneuvering. What does Black buy for his extra risk? His chances of making the 5-point improve from 28% (if he hits only one man with 13/5*) to 40% if he hits two men. Is the gain worth the risk? It's impossible to say precisely, but my preference is for 13/5*, leaving a cleaner position. Score 2 points if you chose that play.

Give yourself 1 point for the passive 8/3, 6/3, which leaves the initiative in White's hands. No credit for the feeble 24/16.

2.     . . . 2-1: bar/24*, bar/23
3.     3-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-2.

*   *   *   *   *

bar/23, 8/5

2 points for making the vital 5-point. No credit for making the 22-point.

3.     . . . 2-1: 24/22, 23/22

This is weaker than simply 13/10. White's checkers were in no immediate danger, and with a lead in the race he will be looking for opportunities to run. The anchor on the 22-point could easily turn into a trap.

4.     3-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-1.

*   *   *   *   *

13/10, 6/5

3 points for this nice play. Behind in the race, Black can afford to make the purest possible play to improve his position. This move puts White under considerable pressure since he cannot hit and build his board at the same time.

1 point for 8/4, which starts a valuable point but leaves a stack of checkers on the midpoint. No credit for 23/20, 6/5, which, although it duplicates 5s, forces White to hit and risks losing the initiative. Subtract a point for 24/20. Breaking his anchor could result in a quick annihilation. Black's position is not at all desperate and he has no reason to incur such a risk.

4.     . . . 2-1: 13/10
5.     3-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-3.

*   *   *   *   *

24/18(2)

5 points for this outstanding play. By seizing an anchor in the very center of White's position, Black prevents himself from ever being primed. Black is now free to continue building his own priming position on the other side of the board.

2 points for 24/21(2), 13/10(2), which improves Black's position, but could leave his back checkers stuck if White subsequently makes the 5-point. Only 1 point for 13/7(2). Black's strong forward position could easily be neutralized by White's developing prime on the other side of the board. Also, score 1 point for 13/7, 10/7, 23/20, which has the same drawback.

5.     . . . 5-1: 10/5, 6/5

A mistake. Even though White has no board, the hit is nontheless mandatory (22/17*/16).

6.     6-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-2.

*   *   *   *   *

13/7, 10/8

5 points if you chose this move, which puts White under enormous pressure to throw a 4 next turn. Only 3 points for 10/4, 6/4, which, although it makes a good point, probably won't be sufficient to contain White's back checkers. White would have 5s to hit on the 17-point, 4s and 6s to hit inside. With the actual play, White has fewer working numbers.

3 points for the hit with 23/15*. Although normally correct, the hit is less effective in this position because White has so many (20) return shots.

6.     . . . 4-2: 22/18*/16

Correct. White must try to break out.

7.     6-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-1.

*   *   *   *   *

bar/18

1 point. 13/7 with the six is not so good since the midpoint is left stripped.

7.     . . . 5-4: 10/5, 6/2*

Not a bad play, but 22/13 is a little better, despite the lack of duplication in the outfield. If White is not hit, he would become a favorite in the game since his back checkers have escaped. His actual play won't make him a favorite whatever Black throws in return.

8.     2-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 2-1.

*   *   *   *   *

bar/23*/22

1 point for the only reasonable play.

8.     . . . 2-1: bar/22
9.     6-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-2.

*   *   *   *   *

22/16, 18/16

1 point.

9.     . . . 6-3: 22/16, 6/3
10.     6-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-1.

*   *   *   *   *

13/7, 8/7

2 points for this play, which tries to build an attacking position while White still has an exposed blot in his home board. 1 point for the less aggressive 13/6.

10.     . . . 6-4: 22/16, 8/4
11.     3-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-2.

*   *   *   *   *

16/14, 16/13

4 points. Black has too many outfield points. He needs to hold two points while waiting for a shot, but has no need for three. This roll is a perfect opportunity to break an extraneous point, while White has two home-board blots. Only 1 point for the seemingly obvious 7/4, 6/4, which could lead to an awkward squeeze in a few more moves.

11.     . . . 5-2: 16/11*, 5/3
12.     6-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-1.

*   *   *   *   *

bar/24, 13/7

3 points for this play, which maintains pressure on the blot on the 21-point. No credit for bar/18, which leaves White free to maneuver.

12.     . . . 5-1: 11/5
13.     5-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 5-3.

*   *   *   *   *

24/21*/16

2 points. Black still needs the midpoint to connect his forces, so no credit for playing 13/8 with the five.

13.     . . . 4-2: bar/23, 13/9*
14.     4-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 4-3.

*   *   *   *   *

bar/18

White now has the stronger home board, so Black has to tread a fine line between caution and agressiveness. 2 points for this move, which leaves only one blot. Black threatens to make real progress if White doesn't throw a six. Subtract a point for bar/21, 5/2*, which leave three blots. Black could be wiped out if White returns with a two.

14.     . . . 4-3: 9/2
15.     6-1
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-1.

*   *   *   *   *

8/7/1

2 points for this play, which avoids being hit, but 2 points for the equally good 8/2*/1, which leaves White with some very awkward return numbers (5-1, 4-2, and 5-2).

15.     . . . 6-3: 23/17, 5/2
16.     5-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 5-3.

*   *   *   *   *

18/13, 7/4

Black realizes that a hit is too dangerous in view of White's 4-point board. 2 points if you chose this waiting play. Subtract a point for 13/8*/5, which could lose on the spot.

16.     . . . 6-5: 17/11, 16/11
17.     2-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 2-2.

*   *   *   *   *

13/9*, 6/4, 13/11

5 points for this very fine move. Playing the last two 13/11, rather than 9/7, shows real insight. Black needs to make a 5-point prime to contain White's last checker. By moving 13/11, Black leaves himself with three builders aiming at the 8-point. After the conservative 9/7, Black has only a small chance of making the 8-point and no better chance of making the 3-point. The duplication of ones makes the play a bit less risky than might appear.

1 point only for the pedestrian 13/9*/7, 6/4.

17.     . . . 6-1: bar/24*, 11/5
18.     4-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 4-3.

*   *   *   *   *

bar/18

1 point.

18.     . . . 5-2: 24/22, 11/6
19.     3-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-2.

*   *   *   *   *

11/9, 13/10

2 points. No credit for 5/3*, 9/6, which accomplishes less at more risk.

19.     . . . 3-3: 13/10(2), 6/3, 5/2
20.     6-4:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-4.

*   *   *   *   *

18/14, 10/4

No credit for this oversight. 2 points for the obviously stronger 9/3, 7/3.

20.     . . . 4-3: 8/5, 8/4
21.     6-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-2.

*   *   *   *   *

9/3*, 5/3

1 point.

21.     . . . 4-1: bar/24, 5/1
22.     2-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 2-1.

*   *   *   *   *

14/12, 9/8

2 points for this play, slotting the prime from the back. Black should make this play even if 6-1 was an outright winner for White, which it obviously isn't here. No credit for any other play.

22.     . . . 4-1: 24/23, 5/1
23.     1-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 1-1.

*   *   *   *   *

12/8

2 points. Black assures the win and still maintains some gammon chances. Subtract 2 points for any play involving 4/2*; Black could easily lose the game if White returns with a two.

23.     . . . 3-2: 6/4, 5/2
24.     6-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
     
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-2.

*   *   *   *   *

8/2*, 4/2

2 points for this play, or for 4/2*, 18/12, or for 18/10. Each play tries to win a gammon by a different method. By making the 2-point, Black hopes to keep White's two men on the 10-point from ever entering his home board before closeout. Hitting loose inside might pick up a second checker after a return hit. Moving 18/10 hopes to catch a second checker as White breaks the 10-point. A simulation indicated that each play had about a 10% chance of winning a gammon.

24.     . . . (no play)
25.     2-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 2-2.

*   *   *   *   *

18/12, 8/6

1 point.

25.     . . . (no play)
26.     3-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-2.

*   *   *   *   *

6/1

2 points. Black goes directly for the closeout, and also has chances to catch a second (or even third) checker if White rolls 6-1. 1 point for 12/7, which is another reasonable approach.

26.     . . . 5-1: bar/24*, 6/1
27.     (no play) 6-3: 10/7*, 10/4
28.     (no play) 5-2: 7/2, 4/2

A mistake. Correct is 7/2, 3/1, preserving a three.

29.     6-1: bar/19 4-3: 4/1
30.     5-4:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 5-4.

*   *   *   *   *

bar/21*, 7/2

3 points. Black now has two builders aiming at the ace-point, maximizing his chances for closing out both checkers. No credit for any other play.

30.     . . . (no play)
31.     6-6:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-6.

*   *   *   *   *

19/1*, 7/1

1 point.

31.     . . . (no play)
32.     6-4:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 6-4.

*   *   *   *   *

21/11

1 point. Also score 1 point for 12/6, 21/17.

32.     . . . (no play)
33.     3-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-3.

*   *   *   *   *

12/6, 11/5

1 point.

33.     . . . (no play)
34.     3-1:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-1.

*   *   *   *   *

6/3, 5/4

1 point.

34.     . . . (no play)
35.     5-3:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 5-3.

*   *   *   *   *

6/3, 6/1

1 point. 3 points for the more accurate 5/off, 5/2, which gives the best chance of winning the gammon at little risk.

35.     . . . (no play)
36.     6-2: 5/off, 5/3 6-2: bar/19
37.     3-2:
13 14 15 16 17 18 19 20 21 22 23 24
   
   
12 11 10 9 8 7 6 5 4 3 2 1
Black to play 3-2.

*   *   *   *   *

3/off, 2/off

3 points. Black's chances of being hit as a result of this play are quite small: White must dance (probability 16/36), Black must then leave a shot (probability 6/36), and White must then hit the blot (probability 11/36). The combined probability of these events is about 2%, and Black is still a favorite to win the game even in that event. Since Black remains with an even number of men after bearing off two, the risk is justified for the extra chance at a gammon.

37.     . . . (no play)
38.     4-3: 4/off, 3/off 6-2: bar/17
39.     3-3: 3/off(3), 4/1 2-2: 19/11
40.     3-1: 4/off 5-5: 17/2, 11/6
Single game

*   *   *

Scoring Guide
64–70 Congratulations. You play as well as you think you do.
55–64 Quite good.
50–54 Average.
40–49 Your game needs some work.
Below 40 Back to the drawing boards.

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