All you need to know about Carpenter's Square-21 |
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Previous | Index | Next Diagram 21.1: Black to play Let us discuss this corner shape seemingly weakened by . Suppose white just plays , how can black respond? Diagram 21.2: White fails is incorrect, but is wrong too. is the key point and black is alive. Diagram 21.3: Black fails occupies the key point instead. is the most tricky answer (clearly or not working). Although is a good move (a common tesuji to avoid those big-eye killing shapes), it doesn't work here...... Diagram 21.3: Black fails (continued) is a calm move. Black is killed. Diagram 21.4: Solution It becomes clear now that is the key point. If white plays , black has a number of forcing moves, followed by . Diagram 21.5: Solution (continued) can be a tesuji sometimes. But because of the external liberty at 'a', black can use Oshi-tsubushi tesuji to kill the white stones. Diagram 21.6: Black fails also looks like a key point, but so is . If black chooses , white can form almost a picnic ko. Black clearly fails. Diagram 21.7: Black fails too here is better. After there is just enough room for black to make two eyes. Black is successful in a pure life & death sense. But comparing to Diagram 21.4, black is almost 10 points worse off so I cannot accept this as an alternative solution. Diagram 21.8: White fails is slightly more challenging. is incorrect. Black can play and the corner is completely alive. Diagram 21.9: Same as Diagram 21.6 Apparently is the key point. This results the same as Diagram 21.6. Diagram 21.10: Black fails doesn't work and the corner is killed by . Conclusion: Diagram 21.4 is the only right solution. Luckily it is not hard to memorise that: is almost always the key point for Carpenter's Square shapes. Previous | Index | Next |