Life In 19x19

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[go]$$W White kills
$$ ------------------+
$$ . . . O . . . . . |
$$ X . O . O X X X . |
$$ . . . O X O O O 6 |
$$ X . . O X X X 1 . |
$$ . . . O X . 2 . 3 |
$$ X . . O X O X X 4 |
$$ . . . X O 7 O O 5 |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]

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[go]$$W White captures four stones ( @ )
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . O O O . O . . . . . . |
$$ . . . O X X O . . . . . . . |
$$ . O O X 4 3 X O O O O . . . |
$$ . O X 2 X . X O X 7 9 O O . |
$$ . O X . 1 6 5 X . X X X O . |
$$ ----------------------------+[/go]

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[go]$$W @ White kills if black persists ('a' is auto-atari)
$$ +---------------------------------------+
$$ | . . . X . . 3 4 X 1 2 8 7 . . . . . . |
$$ | . . X O O O 5 X O X . X O X X O . . . |
$$ | . X . X O . O O O X a X X O O O . . . |
$$ | . . . X O . O X O O 9 X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

Black cannot play like the above, so:

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[go]$$W elsewhere. White lives, and gets to play 'a' later
$$ +---------------------------------------+
$$ | . . . X . . 3 a X 1 2 . . . . . . . . |
$$ | . . X O O O . X O X . X O X X O . . . |
$$ | . X . X O . O O O X . X X O O O . . . |
$$ | . . . X O . O X O O . X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

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[go]$$W Reference diagram
$$ +---------------------------------------+
$$ | . . . X 5 . 1 2 X 4 . . . . . . . . . |
$$ | . . X O O O 3 X O X . X O X X O . . . |
$$ | . X . X O . O O O X . X X O O O . . . |
$$ | . . . X O . O X O O . X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

This way to live is simple but uninspired. The main line above gains several points compared to this.

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[go]$$W White to play
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | 7 3 O . . . . . .
$$ | 2 X O X . . . . .
$$ | 1 . X O O . . . .
$$ | . X X X O . . . .
$$ | X O X X O . . . .
$$ | . O X O O . . . .
$$ | O . O X . O . . .
$$ | 5 O O X X X . . .
$$ | 4 X X O X O . X .
$$ | . . 6 O X . . . .
$$ | . . . . . . . . .
$$ +------------------[/go]

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[go]$$W White to play
$$ ------------------+
$$ . . . O . . . . . |
$$ X . O . O X X X . |
$$ . . . O X O O O 6 |
$$ X . . O X X X 1 . |
$$ . . . O X . 2 . 3 |
$$ X . . O X O X X 4 |
$$ . . . X O 7 O O 5 |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]

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[go]$$W White to play
$$ ------------------+
$$ . . . O . . . . . |
$$ X . O . O X X X . |
$$ . . . O X O O O . |
$$ X . . O X X X 1 . |
$$ . . . O X . 2 . 3 |
$$ X . . O X O X X 4 |
$$ . . . X O . O O 5 |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]

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[go]$$W White to play
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . O O O . O . . . . . . |
$$ . . . O X X O . . . . . . . |
$$ . O O X . . X O O O O . . . |
$$ . O X . X . X O X . . O O . |
$$ . O X . . . . X . X X X O . |
$$ ----------------------------+[/go]

Tenuki because I cannot find anything

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[go]$$W White to play
$$ +---------------------------------------+
$$ | . . . X 5 . 1 2 X 4 . . . . . . . . . |
$$ | . . X O O O 3 X O X . X O X X O . . . |
$$ | . X . X O . O O O X . X X O O O . . . |
$$ | . . . X O . O X O O . X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

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[go]$$W White to play
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . 7 O . . . . . .
$$ | . X O X . . . . .
$$ | . 4 X O O . . . .
$$ | 3 X X X O . . . .
$$ | X O X X O . . . .
$$ | 1 O X O O . . . .
$$ | O . O X . O . . .
$$ | 5 O O X X X . . .
$$ | 2 X X O X O . X .
$$ | . . 6 O X . . . .
$$ | . . . . . . . . .
$$ +------------------[/go]

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[go]$$W White to play
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | 7 5 O . . . . . .
$$ | 6 X O X . . . . .
$$ | 3 4 X O O . . . .
$$ | 2 X X X O . . . .
$$ | X O X X O . . . .
$$ | 1 O X O O . . . .
$$ | O . O X . O . . .
$$ | . O O X X X . . .
$$ | . X X O X O . X .
$$ | . . . O X . . . .
$$ | . . . . . . . . .
$$ +------------------[/go]

EDIT: Hmm there may be another variation for black creating ko (unless I am totally out of tune )

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[go]$$W White to play
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . O . . . . . .
$$ | . X O X . . . . .
$$ | 6 4 X O O . . . .
$$ | 3 X X X O . . . .
$$ | X O X X O . . . .
$$ | 1 O X O O . . . .
$$ | O . O X . O . . .
$$ | 5 O O X X X . . .
$$ | 2 X X O X O . X .
$$ | . . 7 O X . . . .
$$ | . . . . . . . . .
$$ +------------------[/go]

Correct.

#1 Correct.
#3 White can do better.
#4 In response to , black will push out along the second line to escape (at in your first solution diagram), as the white group still has only one eye...

HermanHiddema wrote:@entropi:
#4 In response to , black will push out along the second line to escape (at in your first solution diagram), as the white group still has only one eye...

Another try:

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[go]$$W White to play
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . 3 O . . . . . .
$$ | . X O X . . . . .
$$ | 1 2 X O O . . . .
$$ | . X X X O . . . .
$$ | X O X X O . . . .
$$ | . O X O O . . . .
$$ | O . O X . O . . .
$$ | . O O X X X . . .
$$ | . X X O X O . X .
$$ | . . . O X . . . .
$$ | . . . . . . . . .
$$ +------------------[/go]

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[go]$$W White to play
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | 7 3 O . . . . . .
$$ | 2 X O X . . . . .
$$ | 1 . X O O . . . .
$$ | . X X X O . . . .
$$ | X O X X O . . . .
$$ | . O X O O . . . .
$$ | O . O X . O . . .
$$ | 5 O O X X X . . .
$$ | 4 X X O X O . X .
$$ | . . 6 O X . . . .
$$ | . . . . . . . . .
$$ +------------------[/go]

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[go]$$W White to play
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . O O O . O . . . . . . |
$$ . . . O X X O . . . . . . . |
$$ . O O X 4 3 X O O O O . . . |
$$ . O X 2 X . X O X 7 9 O O . |
$$ . O X . 1 6 5 X 8 X X X O . |
$$ ----------------------------+[/go]

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[go]$$W White to play
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . |
$$ . . . O O O . O . . . . . . |
$$ . . . O X X O . . . . . . . |
$$ . O O X 4 3 X O O O O . . . |
$$ . O X . X . X O X 5 7 O O . |
$$ . O X . 1 2 . X 6 X X X O . |
$$ ----------------------------+[/go]

White captures 4 stones.

Yes, now it is correct

Correct.

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[go]$$W White to play =
$$ +---------------------------------------+
$$ | . . . X . . 1 2 X 3 4 8 7 . . . . . . |
$$ | . . X O O O 5 X O X . X O X X O . . . |
$$ | . X . X O . O O O X a X X O O O . . . |
$$ | . . . X O . O X O O 9 X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

above will not happen...
so black will let white live by giving up three stone.

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[go]$$W White to play =
$$ +---------------------------------------+
$$ | . . . X . . 1 2 X 3 4 . . . . . . . . |
$$ | . . X O O O . X O X . X O X X O . . . |
$$ | . X . X O . O O O X . X X O O O . . . |
$$ | . . . X O . O X O O . X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

infact white should tenuki and take sente because it is alive.. ??

Yes, basically correct, but black should only give one stone, of course, and take sente:

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[go]$$W is sente
$$ +---------------------------------------+
$$ | . . . X . . 1 3 X 2 . . . . . . . . . |
$$ | . . X O O O . X O X . X O X X O . . . |
$$ | . X . X O . O O O X . X X O O O . . . |
$$ | . . . X O . O X O O . X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

So white should throw in first, as it is free and may give better endgame later:

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[go]$$W White can play a at any time to create aji.
$$ +---------------------------------------+
$$ | . . . X . . 3 . X 1 2 . a . . . . . . |
$$ | . . X O O O . X O X . X O X X O . . . |
$$ | . X . X O . O O O X . X X O O O . . . |
$$ | . . . X O . O X O O . X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

The following resistance is pointless and loses sente:

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[go]$$W at , at
$$ +---------------------------------------+
$$ | . . . X . 9 2 . X 1 3 6 . . . . . . . |
$$ | . . X O O O 5 X O X 4 X O X X O . . . |
$$ | . X . X O . O O O X . X X O O O . . . |
$$ | . . . X O . O X O O 0 X O . . , . . . |
$$ | . . . X O O X X X O O X O . . . . . . |
$$ | . . . X . X . . . X X O O . . . . . . |
$$ | . . . . . . X . . . . . . . . . . . . |[/go]

As I've mentioned before I tend to fixate on insignificant details. A question for Herman (or anyone else, really) on question 2: I'm wondering whether one should use the first moves in that sequence as ko threats. Would you ignore the situation for as long as possible in the hope that your opponent has missed the sequence and might miss the opportunity to defend, or would you use the beginning of that sequence as medium-sized ko threats long before finishing the sequence became profitable?

if i can sense that my opponent misread then i usually (all depends on the situation) wait till the end to trigger the unexpected bomb

Since the profit is rather small, 8 points gote, #2 is very much an endgame sequence. Using the first three moves as ko threats in the middle game is therefore entirely feasible, as each of these move threatens to kill the entire group.

In the endgame, I would usually just play it when it gets big enough. Perhaps, if I were slightly behind, I might leave it and hope my opponent missed it

HermanHiddema wrote:Perhaps, if I were slightly behind, I might leave it and hope my opponent missed it

Thanks! I always forget about the whole "knowing who's ahead" thing!