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Problem of the Week #87: Solution
12-15-2010
, 06:57 PM
Problem of the Week #87: Solution
Cash game, Center cube.
Black to play 6-2.
Note: All ‘cash game’ problems assume the Jacoby Rule is in effect. That is, you can’t win a gammon unless the cube has been turned.
Problem 87 is an example of what we’ve labeled the proto-backgame. Both sides have been busy whacking each other for a while, with the result that Black now has seven men back, and White has three. Neither side has managed to make either a new home-board point or a new blocking point, so each side is free to maneuver, and the cost of getting another man hit is very small. Now Black has a 6-2 to play from the bar. Clearly he’ll come in with Bar/23, after which he can choose among five legal sixes, none of which are absurd. It’s a tough problem, to be sure.
Let’s start by reviewing the key ideas for handling proto-backgame positions. After that, we’ll list Black’s five legal choices and see how they stack up. Although none of Black’s plays are horrible, some will drop off our radar screen quickly once we see what we’re really trying to do.
Key Idea #1: Don’t kill checkers. This rule is important in all types of games, but it’s especially important in proto-backgames. You must keep your checkers active and in front of your opponent. Burying checkers on your 1-point and 2-point is death; don’t do it.
Key Idea #2: Make your opponent play the backgame. A common mistake in proto-backgames is assuming that the player who initially has the most men back will inevitably be the one playing the backgame. These positions, however, usually lack any defined structure because so much of the early game is spent hitting and being hit. Without structure, it’s relatively easy for the side with more men back to get a lucky hit or two and reverse the situation. To paraphrase General Patton: “Don’t play a backgame; make the other poor bastard play a backgame.”
Key Idea #3: Make strong points. All the points that are normally good to make in the opening are even better to make in a proto-backgame. Your blocking points (the 4, 5, 7, and 9-points) are even stronger because there are more checkers to block. Your anchors (the 21, 20, and 19-points) are even better because you have more checkers to recirculate to the outfield.
Key Idea #4: Recirculate. Don’t fall in love with backgame points; keep your checkers moving to your opponent’s outfield. From his outfield, you’re threatening to make points in your outfield, which are blocks for whatever men he has back.
Key Idea #5: Watch out for your middling doubles. Check your position to see if particular numbers are blocked around the board. If that’s the case, your game could blow up with an awkward double. The problem won’t come from 1-1 or 2-2, which are small enough to be handled in most positions. It also won’t come from 6-6 or 5-5, since your opponent won’t have had a chance to form a prime yet. The real danger numbers in proto-backgames are 3-3 and 4-4, which are susceptible to the kind of small blocks that form in these positions. Usually the culprit is a careless play earlier, where an accurately-played ace or deuce could create a position where all numbers play well.
That’s a general summary of the ideas to keep in mind when both sides have a bunch of men back but no real structure yet. Now let’s look at Black’s actual options and see which play makes the most sense.
Bar/23 24/18. Moving out to the 18-point is the worst play. It doesn’t hit, doesn’t make a new point, and leaves two blots on the points White most wants to make, his 7-point and 9-point. White now has a few point-making numbers and lots of double-hits, which often result in White’s building a quick little prime. This is exactly what Black wants to avoid.
Bar/23 16/10. This is an improvement on 24/18, since Black doesn’t leave blots where White is trying to make points. In addition, the blot on the 10-point puts a little pressure on some points Black would like to make, which is good. Still, the play has two significant downsides:
> White gets to hit with threes, which is currently his least effective number around the board.
> The move leaves Black a little thin in White’s outfield, with no presence there and a stripped midpoint.
Bar/23 13/7*. This was the play I actually chose when the position came up. (It’s from a match against Nack Ballard at one of the Reno Invitationals back in the late 1980s). I realized breaking the midpoint was dangerous, but I saw that the 23-point was an awkward point for White to have a couple of checkers. I thought if I could make a small block of three points, White might get squeezed, needing to build some front points quickly while at the same time needing to move his back men.
That’s exactly how the game played out, so I thought I had made a really good move. Years later, when Snowie had gotten good enough in backgames to trust its rollouts, I realized that the play was just too loose. The three blots on my bar-point, midpoint, and 16-point give White too much of an opportunity to stick me in a true backgame. My move does win more games than the second-best play, but loses too many gammons.
Bar/23 22/16. Not a bad play. It keeps the 20-point and makes the 16-point, giving Black a good anchor and a clear route to the outfield. The downside of the play is that Black is consolidating into an inferior position. White has a lot of rolls to make a good point somewhere, and this play leaves Black more likely to end up in some sort of backgame/holding game. Since White still has no structure, Black is entitled to play more aggressively.
Bar/23 20/14*. This is the right idea when White has no new structure: hit to keep White off balance and gain ground in the race. Hitting gains 14 pips, so instead of trailing by 34 pips in the race, Black will trail by only 20. After another such sequence, Black could actually catch up, and that’s a great result. You always want to make your opponent play the backgame, not you, and this is the best play to get out of backgame mode as soon as possible.
Leaving the 20-point carries some risk, but it’s very small; White needs to roll an immediate 1-1 or 3-3 to make the point. Otherwise, Black has a triple shot to remake it. Meanwhile, Black picks up some builders to make a point in his outfield. This play gives Black the best overall distribution and board control, and beats out 22/16 by a modest margin.
Solution: Bar/23 20/14*
Cash game, Center cube.
Black to play 6-2.
Note: All ‘cash game’ problems assume the Jacoby Rule is in effect. That is, you can’t win a gammon unless the cube has been turned.
Problem 87 is an example of what we’ve labeled the proto-backgame. Both sides have been busy whacking each other for a while, with the result that Black now has seven men back, and White has three. Neither side has managed to make either a new home-board point or a new blocking point, so each side is free to maneuver, and the cost of getting another man hit is very small. Now Black has a 6-2 to play from the bar. Clearly he’ll come in with Bar/23, after which he can choose among five legal sixes, none of which are absurd. It’s a tough problem, to be sure.
Let’s start by reviewing the key ideas for handling proto-backgame positions. After that, we’ll list Black’s five legal choices and see how they stack up. Although none of Black’s plays are horrible, some will drop off our radar screen quickly once we see what we’re really trying to do.
Key Idea #1: Don’t kill checkers. This rule is important in all types of games, but it’s especially important in proto-backgames. You must keep your checkers active and in front of your opponent. Burying checkers on your 1-point and 2-point is death; don’t do it.
Key Idea #2: Make your opponent play the backgame. A common mistake in proto-backgames is assuming that the player who initially has the most men back will inevitably be the one playing the backgame. These positions, however, usually lack any defined structure because so much of the early game is spent hitting and being hit. Without structure, it’s relatively easy for the side with more men back to get a lucky hit or two and reverse the situation. To paraphrase General Patton: “Don’t play a backgame; make the other poor bastard play a backgame.”
Key Idea #3: Make strong points. All the points that are normally good to make in the opening are even better to make in a proto-backgame. Your blocking points (the 4, 5, 7, and 9-points) are even stronger because there are more checkers to block. Your anchors (the 21, 20, and 19-points) are even better because you have more checkers to recirculate to the outfield.
Key Idea #4: Recirculate. Don’t fall in love with backgame points; keep your checkers moving to your opponent’s outfield. From his outfield, you’re threatening to make points in your outfield, which are blocks for whatever men he has back.
Key Idea #5: Watch out for your middling doubles. Check your position to see if particular numbers are blocked around the board. If that’s the case, your game could blow up with an awkward double. The problem won’t come from 1-1 or 2-2, which are small enough to be handled in most positions. It also won’t come from 6-6 or 5-5, since your opponent won’t have had a chance to form a prime yet. The real danger numbers in proto-backgames are 3-3 and 4-4, which are susceptible to the kind of small blocks that form in these positions. Usually the culprit is a careless play earlier, where an accurately-played ace or deuce could create a position where all numbers play well.
That’s a general summary of the ideas to keep in mind when both sides have a bunch of men back but no real structure yet. Now let’s look at Black’s actual options and see which play makes the most sense.
Bar/23 24/18. Moving out to the 18-point is the worst play. It doesn’t hit, doesn’t make a new point, and leaves two blots on the points White most wants to make, his 7-point and 9-point. White now has a few point-making numbers and lots of double-hits, which often result in White’s building a quick little prime. This is exactly what Black wants to avoid.
Bar/23 16/10. This is an improvement on 24/18, since Black doesn’t leave blots where White is trying to make points. In addition, the blot on the 10-point puts a little pressure on some points Black would like to make, which is good. Still, the play has two significant downsides:
> White gets to hit with threes, which is currently his least effective number around the board.
> The move leaves Black a little thin in White’s outfield, with no presence there and a stripped midpoint.
Bar/23 13/7*. This was the play I actually chose when the position came up. (It’s from a match against Nack Ballard at one of the Reno Invitationals back in the late 1980s). I realized breaking the midpoint was dangerous, but I saw that the 23-point was an awkward point for White to have a couple of checkers. I thought if I could make a small block of three points, White might get squeezed, needing to build some front points quickly while at the same time needing to move his back men.
That’s exactly how the game played out, so I thought I had made a really good move. Years later, when Snowie had gotten good enough in backgames to trust its rollouts, I realized that the play was just too loose. The three blots on my bar-point, midpoint, and 16-point give White too much of an opportunity to stick me in a true backgame. My move does win more games than the second-best play, but loses too many gammons.
Bar/23 22/16. Not a bad play. It keeps the 20-point and makes the 16-point, giving Black a good anchor and a clear route to the outfield. The downside of the play is that Black is consolidating into an inferior position. White has a lot of rolls to make a good point somewhere, and this play leaves Black more likely to end up in some sort of backgame/holding game. Since White still has no structure, Black is entitled to play more aggressively.
Bar/23 20/14*. This is the right idea when White has no new structure: hit to keep White off balance and gain ground in the race. Hitting gains 14 pips, so instead of trailing by 34 pips in the race, Black will trail by only 20. After another such sequence, Black could actually catch up, and that’s a great result. You always want to make your opponent play the backgame, not you, and this is the best play to get out of backgame mode as soon as possible.
Leaving the 20-point carries some risk, but it’s very small; White needs to roll an immediate 1-1 or 3-3 to make the point. Otherwise, Black has a triple shot to remake it. Meanwhile, Black picks up some builders to make a point in his outfield. This play gives Black the best overall distribution and board control, and beats out 22/16 by a modest margin.
Solution: Bar/23 20/14*
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