L19 Go Problem Championship: Round 9

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Kirby
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L19 Go Problem Championship: Round 9

Post by Kirby »

Welcome to Round 9 of the L19 Go Problem Championship.

All problems are black to play. As usual, provide your solutions either via hide tags, or direct private message to me.

Problem 1 (3 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ | . . O O . O O X . .
$$ | X O X X X X O X O .
$$ | O . O . O X X X O .
$$ | . . O , O . . . O ,
$$ | . . . . . . O . . .
$$ | . . O . . . . . . .
$$ | . . . . . . . . . .[/go]
Problem 2 (6 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ -----------------
$$ . X O . . . . . |
$$ . X O X X O . . |
$$ . X O O O . . . |
$$ . X . . X . O . |
$$ . . X X . X O X |
$$ . . . . . X X . |
$$ . . . . . . . . |[/go]
Problem 3 (9 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O . O X .
$$ | . . X , . . O X .
$$ | . X X . O . O X .
$$ | . X O O . . O X .
$$ | . . . . . . O X .
$$ ------------------[/go]
Have fun! :salute:
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EdLee
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Post by EdLee »


:study: ( Kirby, problem 2 seems more difficult for me than problem 3. For now, I cannot do better than ko. :) )

:study:
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hyperpape
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Re: L19 Go Problem Championship: Round 9

Post by hyperpape »

Problem 1
Click Here To Show Diagram Code
[go]$$Wc
$$ --------------------
$$ | . 2 W O B . 1 X . .
$$ | X O X X X X . X O .
$$ | O a O . O X X X O .
$$ | . . O , O . . . O ,
$$ | . . . . . . O . . .
$$ | . . O . . . . . . .
$$ | . . . . . . . . . .[/go]
After black captures at the marked stone, :w1: is forced. Then after :b2:, white can't play at both a and the marked white stone, so Black has two eyes.
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Kirby
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Re: L19 Go Problem Championship: Round 9

Post by Kirby »

@EdLee:
Problem 1 looks good.

You are very close to a solution in one of your variations for Problem 2. There's just one subtle thing missing...

Consider a different starting move for Problem 3.
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Kirby
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Re: L19 Go Problem Championship: Round 9

Post by Kirby »

@hyperpape:
Looks good!
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Cassandra
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Re: L19 Go Problem Championship: Round 9

Post by Cassandra »

@ EdLee
Hi, Ed,
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O . O X .
$$ | . . X O . . O X .
$$ | . X X X O 8 O X .
$$ | . X O O O X O X .
$$ | . . O . X X O X .
$$ ------------------[/go]
Wishful thinking ?
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 8 O X .
$$ | . . X O . . O X .
$$ | . X X X O . O X .
$$ | . X O O O X O X .
$$ | . . O . X X O X .
$$ ------------------[/go]
White is alive.

Kind regards
Thomas
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)
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gamesorry
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Re: L19 Go Problem Championship: Round 9

Post by gamesorry »

1.
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ | . . O O 1 O O X . .
$$ | X O X X X X O X O .
$$ | O . O . O X X X O .
$$ | . . O , O . . . O ,
$$ | . . . . . . O . . .
$$ | . . O . . . . . . .
$$ | . . . . . . . . . .[/go]
(Cont'd)
Click Here To Show Diagram Code
[go]$$Wc
$$ --------------------
$$ | . 2 O O X . 1 X . .
$$ | X O X X X X . X O .
$$ | O . O . O X X X O .
$$ | . . O , O . . . O ,
$$ | . . . . . . O . . .
$$ | . . O . . . . . . .
$$ | . . . . . . . . . .[/go]
Variation:
Click Here To Show Diagram Code
[go]$$Wc
$$ --------------------
$$ | . 1 O O X . 2 X . .
$$ | X O X X X X . X O .
$$ | O . O . O X X X O .
$$ | . . O , O . . . O ,
$$ | . . . . . . O . . .
$$ | . . O . . . . . . .
$$ | . . . . . . . . . .[/go]
2.
Click Here To Show Diagram Code
[go]$$Bc
$$ -----------------
$$ . X O . . . . . |
$$ . X O X X O 1 . |
$$ . X O O O 2 3 . |
$$ . X . . X 4 O 5 |
$$ . . X X . X O X |
$$ . . . . . X X . |
$$ . . . . . . . . |[/go]
Variation:
Click Here To Show Diagram Code
[go]$$Bc
$$ -----------------
$$ . X O . . 4 . . |
$$ . X O X X O 1 . |
$$ . X O O O 3 2 5 |
$$ . X . . X 6 O 7 |
$$ . . X X . X O X |
$$ . . . . . X X . |
$$ . . . . . . . . |[/go]
Variation:
Click Here To Show Diagram Code
[go]$$Bc
$$ -----------------
$$ . X O . . . . . |
$$ . X O X X O 1 . |
$$ . X O O O 3 2 5 |
$$ . X . . X 4 O . |
$$ . . X X . X O X |
$$ . . . . . X X . |
$$ . . . . . . . . |[/go]
B fails:
Click Here To Show Diagram Code
[go]$$Bc
$$ -----------------
$$ . X O . . . . . |
$$ . X O X X O 2 6 |
$$ . X O O O 1 3 4 |
$$ . X . . X 5 O . |
$$ . . X X . X O X |
$$ . . . . . X X . |
$$ . . . . . . . . |[/go]
3.
B fails (a and b miai):
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O a O X .
$$ | . . X , . 1 O X .
$$ | . X X . O 4 O X .
$$ | . X O O . 3 O X .
$$ | . . b . 2 . O X .
$$ ------------------[/go]
B fails
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X 7 O 2 O X .
$$ | . . X 4 3 8 O X .
$$ | . X X 5 O . O X .
$$ | . X O O 6 . O X .
$$ | . . . . 1 . O X .
$$ ------------------[/go]
B fails
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 1 O X .
$$ | . . X , . . O X .
$$ | . X X . O . O X .
$$ | . X O O . 3 O X .
$$ | . . 4 . 2 . O X .
$$ ------------------[/go]
Ko (W8 fails):
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 2 O X .
$$ | . . X 5 6 . O X .
$$ | . X X 4 O 7 O X .
$$ | . X O O 3 1 O X .
$$ | . . 8 . 0 9 O X .
$$ ------------------[/go]
However, W8 can make a seki:
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 2 O X .
$$ | . . X 5 6 . O X .
$$ | . X X 4 O 7 O X .
$$ | . X O O 3 1 O X .
$$ | . . 9 0 . 8 O X .
$$ ------------------[/go]
Variation: W2 fails
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 4 O X .
$$ | . . X 5 6 . O X .
$$ | . X X . O 7 O X .
$$ | . X O O . 1 O X .
$$ | . . 3 . 2 . O X .
$$ ------------------[/go]
W2 fails:
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 4 O X .
$$ | . . X , 2 . O X .
$$ | . X X . O 5 O X .
$$ | . X O O 7 1 O X .
$$ | . . 3 6 . . O X .
$$ ------------------[/go]
B fails (seki)
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 2 O X .
$$ | . . X 7 8 . O X .
$$ | . X X 6 O 9 O X .
$$ | . X O O 5 1 O X .
$$ | . . 3 4 . 0 O X .
$$ ------------------[/go]
B fails
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 4 O X .
$$ | . . X . . 3 O X .
$$ | . X X 5 O 8 O X .
$$ | . X O O . 7 O X .
$$ | . . 1 2 6 . O X .
$$ ------------------[/go]
hmm... white seems alive to me?...
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Kirby
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Re: L19 Go Problem Championship: Round 9

Post by Kirby »

@gamesorry:
Problems 1 and 2 are correct.
(spoiler?)
Is there an alternative :b3: for this variation?
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . .
$$ | . . . . X X . . .
$$ | . . . X . . X X .
$$ | . . X . O 4 O X .
$$ | . . X . . 3 O X .
$$ | . X X 5 O 8 O X .
$$ | . X O O . 7 O X .
$$ | . . 1 2 6 . O X .
$$ ------------------[/go]
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Kirby
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Re: L19 Go Problem Championship: Round 9

Post by Kirby »

Solutions and updated leader board are given below.

Problem 1


Problem 2


Problem 3


Leaderboard
  1. gamesorry - 110
  2. EdLee - 71
  3. Schachus - 68
  4. dfan - 61
  5. Shaddy - 49
  6. hyperpape - 26
  7. mongus - 19
  8. Lanrose - 16
  9. jeromie - 13
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