L19 Go Problem Championship: Round 5

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Kirby
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Re: L19 Go Problem Championship: Round 5

Post by Kirby »

Since we started a bit late this week, I'll wait until about 24 hours from now to post solutions.
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hyperpape
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Re: L19 Go Problem Championship: Round 5

Post by hyperpape »

Problem 3
Hard to even know where to start here. Maybe with the right incursions, we can limit White to a dead eye-space near the marked points?
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . . . M M O X .
$$ | . X . X O . O M M O X .
$$ | . X . . X . . M O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
The a and b points are jumping out at me.
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . . . . . O X .
$$ | . X . X O . O a . O X .
$$ | . X . . X ..b . O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . 3 4 . . O X .
$$ | . X . X O . O 1 . O X .
$$ | . X . . X 2 . 5 O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . . . 4 . O X .
$$ | . X . X O 6 O 1 5 O X .
$$ | . X . . X 3 . 2 O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . 3 4 . . O X .
$$ | . X . X O . O 1 . O X .
$$ | . X . . X 2 . 5 O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . 5 7 4 . O X .
$$ | . X . X O 3 O . 6 O X .
$$ | . X . . X . 1 2 O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . 4 . 6 . O X .
$$ | . X . X O 3 O . . O X .
$$ | . X . . X 5 1 2 O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
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gamesorry
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Re: L19 Go Problem Championship: Round 5

Post by gamesorry »

Kirby wrote:@gamesorry:
For Problem 3, did you consider this?
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . . . . . O X .
$$ | . X . X O . O 2 . O X .
$$ | . X . . X . 1 . O . X .
$$ | . . X . . . . . O O X .
$$ ------------------------[/go]
Oops, I overlooked that.

So after 2 B has to play 3, but after W4B5, W has 6 and 8
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X 5 3 . . . O X .
$$ | . X . X O 4 O 2 . O X .
$$ | . X . . X 6 1 . O . X .
$$ | . . X . . 7 8 . O O X .
$$ ------------------------[/go]
Therefore, to prevent 6 and 8, B need to consider something like:
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X 5 3 . . . O X .
$$ | . X . X O 4 O 2 . O X .
$$ | . X . . X 9 6 . O . X .
$$ | . . X . . 8 1 7 O O X .
$$ ------------------------[/go]
B still needs to be careful: B3 fails
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . 6 . 4 8 O X .
$$ | . X . X O . O 3 5 O X .
$$ | . X . . X . 2 7 O . X .
$$ | . . X . . . 1 . O O X .
$$ ------------------------[/go]
Therefore, B3 should:
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . 3 . . . O X .
$$ | . X . X O . O 4 . O X .
$$ | . X . . X . 2 . O . X .
$$ | . . X . . . 1 5 O O X .
$$ ------------------------[/go]
(Please deduct at least half of the points even if this is correct.)
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Kirby
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Re: L19 Go Problem Championship: Round 5

Post by Kirby »

Solutions and updated leader board are given below.

Problem 1


Problem 2


Problem 3


Leaderboard
  1. gamesorry - 82
  2. Shaddy - 49
  3. Schachus - 43
  4. EdLee - 38
  5. dfan - 25
  6. Lanrose - 16
  7. hyperpape - 15
  8. jeromie - 13
  9. mongus - 10
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gamesorry
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Re: L19 Go Problem Championship: Round 5

Post by gamesorry »

Ah, I excluded the correct answer in the beginning due to the following W2:
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . X X X X . . .
$$ | . . . . X O O O O X X .
$$ | . . . X . 1 . . . O X .
$$ | . X . X O . O 2 . O X .
$$ | . X . . X a b . O . X .
$$ | . . X . . . c . O O X .
$$ ------------------------[/go]
a and b obviously do not work, but actually c works. However, playing c first doesn't work. Nice problem!
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Kirby
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Re: L19 Go Problem Championship: Round 5

Post by Kirby »

That C1 stone is nice :-)

But yeah, I think the 3rd problem here was pretty tricky. The next couple of rounds should be a bit easier.

It's hard to find the ideal difficulty for each problem, so I usually try to mix it up (sometimes easier, sometimes harder).
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