Life In 19x19

2017 Round 2.1 (004)

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[go]$$B B kills
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . O X . . . . .
$$ | 4 O X , . . . .
$$ | 1 X O X . . . .
$$ | 2 O O X . X . .
$$ | . 5 3 . . . . .
$$ ----------------[/go]

2017 Round 2.2 (005)

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[go]$$B First feelings: (a) or (b)
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | a O . . . O X .
$$ | . b . . O . . .
$$ | ---------------[/go]

Hane:Clamp:2017 Round 2.3 (006)

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[go]$$B W lives
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X 3 1 2 O . X ,
$$ | . . . X O . . O X .
$$ | . X . X O . . O X .
$$ | . . . . 4 . . O . .
$$ --------------------[/go]

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[go]$$B W lives
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , . . O . X ,
$$ | . . . X O 2 . O X .
$$ | . X . X O 1 . O X .
$$ | . . . . . . . O . .
$$----------------------[/go]

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , . . O . X ,
$$ | . . . X O 1 . O X .
$$ | . X . X O . . O X .
$$ | . . . . . . . O . .
$$----------------------[/go]

Your solution for #1 is correct. Looks like you're still investigating the other two, so I won't comment on those.

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[go]$$B
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . O X . . . . .
$$ | 4 O X , . . . .
$$ | 1 X O X . . . .
$$ | 2 O O X . X . .
$$ | . 5 3 . . . . .
$$ ----------------[/go]

I was able to work a little on problem 2 as well

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[go]$$B First version W lives
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | 2 O 3 4 . O X .
$$ | . 1 5 . O . . .
$$ ----------------[/go]

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

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[go]$$B
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | O O O O . O X .
$$ | O . 9 . O X . .
$$ ----------------[/go]

I'm unsure about this result so I'm going to continue hunting for something better

Your solution for problem 1 is correct.

For the second problem, continuing from your last diagram, if white captures the stone...?

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[go]$$B
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | O O O O . O X .
$$ | O . 9 . O C 0 .
$$ ----------------[/go]

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[go]$$B
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | O O O O . O X .
$$ | O . 1 . O 4 2 3
$$ ----------------[/go]

For some reason I thought this would be a Ko fight but I see that white will just play and live.

While driving though i was able to come up with this sequence

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[go]$$B same as before
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | 2 O 4 6 . O X .
$$ | 8 1 3 5 O 7 . .
$$ ----------------[/go]

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[go]$$B Ko fight
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | O O O O 3 O X .
$$ | O . 2 . O 1 . .
$$ ----------------[/go]

I don't know if this is the best sequence for black but it at least forces a ko fight

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[go]$$B
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | 2 O 4 . 6 O X .
$$ | . 1 3 5 O . . .
$$ ----------------[/go]

Anyway, the solution for this one should avoid both ko and seki, since there is a way to kill directly.

Problem 1

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[go]$$B
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . O X . . . . .
$$ | . O X , . . . .
$$ | 1 X O X . . . .
$$ | 2 O O X . X . .
$$ | . a 3 . . . . .
$$ ----------------[/go]

White can't play at a for a second eye due to a shortage of liberties

Problem 2

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[go]$$B
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | a O . c . O X .
$$ | . b . . O . . .
$$ ----------------[/go]

This reminds me of this problem Bill Spight posted a while back. But there's a crucial difference; if black hanes at a here and white decends at b, the resulting shape is dead instead of alive. That suggests to me that black can do better than ko in this problem and that c is a key point.

Here's my answer:

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

Another possible resistance:

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

Problem 3 (9 points)


I think this clamp works:

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , . . O . X ,
$$ | . . . X O 3 . O X .
$$ | . X . X O 1 . O X .
$$ | . . . . 2 a . O . .
$$ --------------------[/go]

The hane at a is answered by the same 3.

If white tries this

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , b . O a X ,
$$ | . . . X O 2 . O X .
$$ | . X . X O 1 4 O X .
$$ | . . . 7 3 5 6 O .
$$ --------------------[/go]

The weakness at a and the shortage of liberties at b ensure white can't get two eyes.

Oops. On problem 3 I missed white's throw in. I've looked at the other contestants' answers, so I'm disqualified from posting another solution.

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , . . O . X ,
$$ | . . . X O 2 . O X .
$$ | . X . X O 1 6 O X .
$$ | . . . 7 3 4 5 O .
$$ --------------------[/go]

1.

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[go]$$B
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . O X . . . . .
$$ | . O X , . . . .
$$ | 1 X O X . . . .
$$ | 2 O O X . X . .
$$ | . a 3 . . . . .
$$ ----------------[/go]

2.

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[go]$$B
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | 3 O 2 1 . O X .
$$ | . . . . O . . .
$$ ----------------[/go]

Incidentally, I just found a very similar situation in one of my 13*13 games today:
https://online-go.com/game/6863138 (move 53)

Variation 1: Ko, B fails

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[go]$$B
$$ | . . . . . . . .
$$ | . X X X X . . .
$$ | . X O O O X X .
$$ | 1 O . 2 . O X .
$$ | . 3 4 . O . . .
$$ ----------------[/go]

3.

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , 4 . O . X ,
$$ | . . . X O 7 2 O X .
$$ | . X . X O 3 1 O X .
$$ | . . . . 6 5 . O . .
$$ --------------------[/go]

Variation:

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X 4 . 7 O . X ,
$$ | . . . X O . 2 O X .
$$ | . X . X O 3 1 O X .
$$ | . . . . 5 6 . O . .
$$ --------------------[/go]

Variation:

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X 9 . 4 O 5 X ,
$$ | . . . X O . 3 O X .
$$ | . X . X O . 1 O X .
$$ | . . . . 2 8 6 O 7 .
$$ --------------------[/go]

Variation:

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , 5 . O . X ,
$$ | . . . X O 4 3 O X .
$$ | . X . X O 2 1 O X .
$$ | . . . . . . . O . .
$$ --------------------[/go]

Variation:

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X 7 5 6 O 4 X ,
$$ | . . . X O a 3 O X .
$$ | . X . X O 2 1 O X .
$$ | . . . . 8 . 9 O . .
$$ --------------------[/go]

B fails

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

B fails

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X 3 1 2 O . X ,
$$ | . . . X O . . O X .
$$ | . X . X O . . O X .
$$ | . . . . 4 . . O . .
$$ --------------------[/go]

Looks good for problems 1 & 2.

And, indeed, that throw-in poses an issue from problem 3

Good work! Regarding problem 3, do you have a response for white's connection with , below?

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , 2 . O . X ,
$$ | . . . X O . . O X .
$$ | . X . X O . 1 O X .
$$ | . . . . . . . O . .
$$ --------------------[/go]

Problem 1 (3 points)

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[go]$$B
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . O X . . . . .
$$ | . O X , . . . .
$$ | 1 X O X . . . .
$$ | 2 O O X . X . .
$$ | . . 3 . . . . .
$$ ----------------[/go]

Problem 2 (6 points)

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

Problem 3 (9 points)

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , 4 . O . X ,
$$ | . . . X O . 2 O X .
$$ | . X . X O 3 1 O X .
$$ | . . . . . 5 . O . .
$$ --------------------[/go]

so it's ko with 2 @ 4, 5 @ 2.

Kirby wrote:@gamesorry:

Good work! Regarding problem 3, do you have a response for white's connection with , below?

$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , 2 . O . X ,
$$ | . . . X O . . O X .
$$ | . X . X O . 1 O X .
$$ | . . . . . . . O . .
$$ --------------------

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , 2 . O . X ,
$$ | . . . X O . . O X .
$$ | . X . X O . 1 O X .
$$ | . . . . . . . O . .
$$ --------------------[/go]

Oops, nice move! This should be a ko

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[go]$$B
$$ | . . . . . . . . . .
$$ | . . . X X X . . . .
$$ | . . X O O O X X . .
$$ | . . X , 2 7 O 5 X ,
$$ | . . . X O 4 3 O X .
$$ | . X . X O 6 1 O X .
$$ | . . . . . . . O . .
$$ --------------------[/go]

Not sure I get the causal implication with the "so" in your comment.

The diagrams you provided are correct, and ko is correct for the third problem - but I didn't quite get your comment. With 5@2, where are 3 and 4?