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Problem of the Week #33: Solution
10-25-2009
, 02:52 PM
Problem of the Week #33: October 18
Cash game. Center cube. Black on move.
(a) Black to play 5-4.
(b) Black to play 6-2.
In Problem 33a, Black has no way to safety the blot on his 16-point. In fact, he can’t avoid creating a second blot as well. He has a few reasonable plays: 13/4, 16/11 13/9, 16/11 6/2, 13/8 13/9, and 6/1* 13/9. None of these plays look terribly strong. How should he decide among them?
Most players ask two questions when they’re trying to evaluate plays that leave blots:
(1) How many shots does each play leave?
(2) How important are the points that I am starting by leaving a blot there?
If we start counting shots, we find that the safest play is 6/1* 13/9, which leaves only 19 shots. Then comes 16/11 6/2, which leaves 21, and 16/11 13/9 which leaves 22. Last place goes to 13/4, which leaves 25 shots. The safest play is the least constructive: 6/1* 13/9 actually leaves three blots rather than two, and starts the ace-point, which doesn’t look very good in this position. Arguably the most constructive play is 13/4, which unstacks the midpoint and begins to build the 4-point, but that leaves by far the most shots. At least in this position, the shots versus construction criteria take us in opposite directions.
There’s another criteria, however, which is much more likely to lead us in the right direction. Let’s ask ourselves this question: What checkers will our opponent use to hit, and how much does he want to hit with those checkers?
For instance, suppose we leave the blot on the 16-point. If White hits, he’ll hit from his mid-point. That surrenders a point, but the hit slots the back of his prime and brings down a couple of builders for his inner board. All in all, that’s pretty constructive.
Or suppose we make a play that includes playing 6/2. To hit that blot, White has to use the checker on his 24-point. No harm done there.
But suppose we play 16/11 13/9. Now in order to hit, White has to break his anchor on the 18-point. Oops! The 18-point is White’s only defensive anchor. That hit could be very costly down the road. Not surprisingly, 16/11 13/9 is Black’s best move.
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The right way to attack these problems is to think about the checkers your opponent has to use to hit. In most cases he’ll have some big preferences. Here’s a partial list that illustrates how hits look from your opponent’s point of view.
Your opponent most wants to:
Hit from a stacked point, diversifying.
Hit and create new builders for the inner board.
Hit and threaten to build a prime.
Hit and escape a back checker.
Hit with a spare checker from a point.
Your opponent least wants to:
Hit deep in the home board.
Hit and break a point.
Hit and break a crucial defensive anchor.
As a rule, directly counting shots is an overrated idea. It’s useful at the end of the game, when the boards are strong and getting hit may lead directly to a loss. In the early game and middle game, it’s much less useful. Instead, look at how your opponent will hit you and see if a hit will be constructive or destructive for his position.
Position 33(b) is the same idea in a different form. The play leaving fewest blots and shots is 16/8. However, that play allows White to hit and release the spare on the 22-point, which is very useful for White, giving him a new checker to move. A much better play is 13/7 9/7. Even though it leaves two blots instead of one, it requires White to break a point somewhere to hit. (Not to be overlooked is the fact that it also builds the very strong 7-point.)
Solution:
(a) 16/11 13/9
(b) 13/7 9/7
Cash game. Center cube. Black on move.
(a) Black to play 5-4.
(b) Black to play 6-2.
In Problem 33a, Black has no way to safety the blot on his 16-point. In fact, he can’t avoid creating a second blot as well. He has a few reasonable plays: 13/4, 16/11 13/9, 16/11 6/2, 13/8 13/9, and 6/1* 13/9. None of these plays look terribly strong. How should he decide among them?
Most players ask two questions when they’re trying to evaluate plays that leave blots:
(1) How many shots does each play leave?
(2) How important are the points that I am starting by leaving a blot there?
If we start counting shots, we find that the safest play is 6/1* 13/9, which leaves only 19 shots. Then comes 16/11 6/2, which leaves 21, and 16/11 13/9 which leaves 22. Last place goes to 13/4, which leaves 25 shots. The safest play is the least constructive: 6/1* 13/9 actually leaves three blots rather than two, and starts the ace-point, which doesn’t look very good in this position. Arguably the most constructive play is 13/4, which unstacks the midpoint and begins to build the 4-point, but that leaves by far the most shots. At least in this position, the shots versus construction criteria take us in opposite directions.
There’s another criteria, however, which is much more likely to lead us in the right direction. Let’s ask ourselves this question: What checkers will our opponent use to hit, and how much does he want to hit with those checkers?
For instance, suppose we leave the blot on the 16-point. If White hits, he’ll hit from his mid-point. That surrenders a point, but the hit slots the back of his prime and brings down a couple of builders for his inner board. All in all, that’s pretty constructive.
Or suppose we make a play that includes playing 6/2. To hit that blot, White has to use the checker on his 24-point. No harm done there.
But suppose we play 16/11 13/9. Now in order to hit, White has to break his anchor on the 18-point. Oops! The 18-point is White’s only defensive anchor. That hit could be very costly down the road. Not surprisingly, 16/11 13/9 is Black’s best move.
-------
The right way to attack these problems is to think about the checkers your opponent has to use to hit. In most cases he’ll have some big preferences. Here’s a partial list that illustrates how hits look from your opponent’s point of view.
Your opponent most wants to:
Hit from a stacked point, diversifying.
Hit and create new builders for the inner board.
Hit and threaten to build a prime.
Hit and escape a back checker.
Hit with a spare checker from a point.
Your opponent least wants to:
Hit deep in the home board.
Hit and break a point.
Hit and break a crucial defensive anchor.
As a rule, directly counting shots is an overrated idea. It’s useful at the end of the game, when the boards are strong and getting hit may lead directly to a loss. In the early game and middle game, it’s much less useful. Instead, look at how your opponent will hit you and see if a hit will be constructive or destructive for his position.
Position 33(b) is the same idea in a different form. The play leaving fewest blots and shots is 16/8. However, that play allows White to hit and release the spare on the 22-point, which is very useful for White, giving him a new checker to move. A much better play is 13/7 9/7. Even though it leaves two blots instead of one, it requires White to break a point somewhere to hit. (Not to be overlooked is the fact that it also builds the very strong 7-point.)
Solution:
(a) 16/11 13/9
(b) 13/7 9/7
