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Beginner Exercise 4 Solution
Difficulty: Beginner
KarlKnechtel, filling in a solution.
Quickest explanation (not at all useful to those for whom this was challenging): "1 is tesuji. 2 and 3 are miai for the kill." How I'd explain it to someone a bit below my level: "The throw-in at 1 threatens to capture the marked stone, and black cannot connect because he is in oiotoshi - black 2 at 3 is answered by the capture with white 3 at 2. So black captures, making one eye; but white 3 falsens the other eye."
In easier terms: Black needs two eyes to live. There is already one virtually at a, so white must prevent the centre space from becoming an eye. The sacrifice destroys the shape of that space, acheiving the goal. This problem is small enough that we can consider all the alternatives:
Playing elsewhere is answered by black either at a or b. (b claims an extra point of territory, at the expense of a ko threat for white. The play at a is safe from that, as I'd originally thought, but I managed to confuse myself somehow. Thanks SAS. :) Anyway - see Points Or Ko Threats Discussion for more information about that sort of tradeoff. ) So clearly white has to do something. (Incidentally, the eye around a is an example of what I call a two-space elbow. Not that it really matters.)
One try is to threaten the existing eye; but the capture solves all of black's problems. (Connecting at a would be very bad for black; white doesn't even have to capture.) This is also a throw-in, but it's the wrong one and doesn't help.
Moving to falsen the other eye looks good at first, because black is in atari to start off with. But all black has to do is connect. Again, the two eyes are solid.
This is a copy of the living page "Beginner Exercise 4 Solution" at Sensei's Library. (C) the Authors, published under the OpenContent License V1.0. |