501 Tesuji Problems #338

[cyclops]

$$c B sacrifices the corner in order to connect the rest
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O . O O X . . |
$$ . X O . O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |

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[go]$$c B sacrifices the corner in order to connect the rest
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O . O O X . . |
$$ . X O . O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |[/go]

Book's Solution

$$c main variation
$$ ------------------+
$$ . . 1 3 . . X O . |
$$ . X O . O O X . . |
$$ . X O 2 O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |

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[go]$$c main variation
$$ ------------------+
$$ . . 1 3 . . X O . |
$$ . X O . O O X . . |
$$ . X O 2 O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |[/go]

But is it unique?

$$c B gains one decisive tempo
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O 2 O O X . 3 |
$$ . X O 1 O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |

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[go]$$c B gains one decisive tempo
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O 2 O O X . 3 |
$$ . X O 1 O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |[/go]

$$c continuation: W fails
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O 2 O O X . 3 |
$$ . X O 1 O X X X . |
$$ . O X X X O O X O |
$$ . 6 4 5 . . . O . |
$$ . . X 7 O . O . . |
$$ . . . . . . . . . |

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[go]$$c continuation: W fails
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O 2 O O X . 3 |
$$ . X O 1 O X X X . |
$$ . O X X X O O X O |
$$ . 6 4 5 . . . O . |
$$ . . X 7 O . O . . |
$$ . . . . . . . . . |[/go]

reparation of the problem:

$$c now unique solution
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O . O O X . O |
$$ . X O . O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |

Click Here To Show Diagram Code

[go]$$c now unique solution
$$ ------------------+
$$ . . . . . . X O . |
$$ . X O . O O X . O |
$$ . X O . O X X X . |
$$ . O X X X O O X O |
$$ . . . . . . . O . |
$$ . . X . O . O . . |
$$ . . . . . . . . . |[/go]

[Joaz Banbeck]

$$Wc
$$ ------------------+
$$ . . . . . . . . X O . |
$$ . 5 4 X O O O O X . X |
$$ . . 3 X O X O X X X . |
$$ . . . O X X X O O X O |
$$ . . . 1 . . . . . O . |
$$ . . . . X 2 O . O . . |
$$ . . . . . . . . . . . |

Click Here To Show Diagram Code

[go]$$Wc
$$ ------------------+
$$ . . . . . . . . X O . |
$$ . 5 4 X O O O O X . X |
$$ . . 3 X O X O X X X . |
$$ . . . O X X X O O X O |
$$ . . . 1 . . . . . O . |
$$ . . . . X 2 O . O . . |
$$ . . . . . . . . . . . |[/go]

$$Wc
$$ ------------------+
$$ . . 7 . . . . . X O . |
$$ . 5 4 X O O O O X . X |
$$ . 6 3 X O X O X X X . |
$$ . . 8 O X X X O O X O |
$$ . . . 1 . . . . . O . |
$$ . . . . X 2 O . O . . |
$$ . . . . . . . . . . . |

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[go]$$Wc
$$ ------------------+
$$ . . 7 . . . . . X O . |
$$ . 5 4 X O O O O X . X |
$$ . 6 3 X O X O X X X . |
$$ . . 8 O X X X O O X O |
$$ . . . 1 . . . . . O . |
$$ . . . . X 2 O . O . . |
$$ . . . . . . . . . . . |[/go]

$$Wc
$$ ------------------+
$$ . . O 1 C . . . X O . |
$$ 3 O X X O O O O X . X |
$$ . X 2 X O X O X X X . |
$$ . . X O X X X O O X O |
$$ . . . O . . . . . O . |
$$ . . . . X X O . O . . |
$$ . . . . . . . . . . . |

Click Here To Show Diagram Code

[go]$$Wc
$$ ------------------+
$$ . . O 1 C . . . X O . |
$$ 3 O X X O O O O X . X |
$$ . X 2 X O X O X X X . |
$$ . . X O X X X O O X O |
$$ . . . O . . . . . O . |
$$ . . . . X X O . O . . |
$$ . . . . . . . . . . . |[/go]

None of this works if black has a stone at N19.

[cyclops]

None of this works if black has a stone at N19.

Thx, Joaz. I now see the book's solution, that is N19, is much better. But still after your last diagram black connects at L14 as requested. Though I wouldn't dare to propose it as an alternative solution anymore. Now I try to understand why the initial hane at N19 works so well.