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 Post subject: Joseki tesuji puzzle
Post #1 Posted: Mon Feb 15, 2021 11:01 am 
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Not superhumanly hard to solve like some of the other stuff I've posted. Just hopefully neat and interesting - anyone should feel free to take a shot at this :) . Let's first show how we get to the puzzle.

Starting position:
Click Here To Show Diagram Code
[go]$$Bc Long knight
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . X . . . . .
$$ | . . X . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


White probes, black emphasizes the left, and white chooses a sharp variation.
Click Here To Show Diagram Code
[go]$$Wc Sharp
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . 3 . . X . . . . .
$$ | . . X 1 . . . . . . .
$$ | . . 2 . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Cut and fight:
Click Here To Show Diagram Code
[go]$$Wc Fight fight fight
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . . . 6 7 . . . . . .
$$ | . . O 4 5 X . . . . .
$$ | . . X O 8 . . . . . .
$$ | . . X 9 . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Next, "a" is also some sort of joseki but black makes a different choice instead:
Click Here To Show Diagram Code
[go]$$Bc Inside turn
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . . 1 X O a . . . . .
$$ | . . O X O X . . . . .
$$ | . . X O X . . . . . .
$$ | . . X O . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


And :b3: makes another interesting choice:

Click Here To Show Diagram Code
[go]$$Bc Outside connect
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . . X X O . . . . . .
$$ | . . O X O X . . . . .
$$ | . . X O X 3 . . . . .
$$ | . . X O . . . . . . .
$$ | . . 2 . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


And now white draws out here. Now the question is, can black save the marked stones?
Assume that ladders to the lower right are good for White, so that the cut at "a" does not cause white to collapse outright.

Click Here To Show Diagram Code
[go]$$Bc Draw out
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . c X X O . . . . . .
$$ | . 4 O X O X . . . . .
$$ | . . B O X X . . . . .
$$ | . . B O . . . . . . .
$$ | . b O a . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Dan and upper kyu players should be familiar with the above shape as one that is often hard for black to escape from. Because even with the cut at "a" followed by the atari at "b", black's two stones can only get 3 liberties. White "c" is sente so white will get 4 liberties.

Nonetheless, black tries anyways:

Click Here To Show Diagram Code
[go]$$Bc Black goes for it all
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . 6 X X O 7 . . . . .
$$ | . O O X O X . . . . .
$$ | . . X O X X . . . . .
$$ | . 5 X O 2 . . . . . .
$$ | . 3 O 1 . . . . . . .
$$ | . 8 4 . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


And this brings us to problem 1. Ladders to the lower right are still good for white.

-------------------------------------------------------------------------

Problem 1 - Black to play.

Click Here To Show Diagram Code
[go]$$Bc Problem 1 - Black to play
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . O X X O X . . . . .
$$ | . O O X O X . . . . .
$$ | . . X O X X . . . . .
$$ | . X X O O . . . . . .
$$ | . X O X . . . . . . .
$$ | . O O . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Problem 2 - what should white do instead?

Click Here To Show Diagram Code
[go]$$Wc Problem 2 - White to play
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . O X X O X . . . . .
$$ | . O O X O X . . . . .
$$ | . . X O X X . . . . .
$$ | . X X O O . . . . . .
$$ | . X O X . . . . . . .
$$ | . a O . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


This post by lightvector was liked by 3 people: Dusk Eagle, le_4TC, Uberdude
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 Post subject: Re: Joseki tesuji puzzle
Post #2 Posted: Mon Feb 15, 2021 4:57 pm 
Gosei
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Very cool!

Problem 1

Click Here To Show Diagram Code
[go]$$Bc Problem 1 - Black to play
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . O X X O X 9 . . . .
$$ | . O O X O X 8 0 . . .
$$ | . . X O X X 6 7 . . .
$$ | . X X O O 2 4 5 . . .
$$ | . X O X 1 . 3 . . . .
$$ | . O O . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Click Here To Show Diagram Code
[go]$$Bcm11 Problem 1 - Black to play
$$ ----------------------
$$ | . . . . . . . 4 5 . .
$$ | . O X X O X X 2 3 . .
$$ | . O O X O X O O 1 . .
$$ | . . X O X X O X . . .
$$ | . X X O O O O X . . .
$$ | . X O X X . X . . . .
$$ | . O O . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Problem 2

This crazy move seems to work, which only becomes apparent after you've thought through problem 1.

Click Here To Show Diagram Code
[go]$$Wc Problem 2 - White to play
$$ ----------------------
$$ | . . . . 1 . . . . . .
$$ | . O X X O X . . . . .
$$ | . O O X O X . . . . .
$$ | . . X O X X . . . . .
$$ | . X X O O . . . . . .
$$ | . X O X . . . . . . .
$$ | . a O . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]

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Each of us woke up one moment and here we were in the darkness.
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No understanding of what is now, no knowledge of what will be.


This post by Dusk Eagle was liked by 5 people: Bill Spight, dhu163, le_4TC, lightvector, SoDesuNe
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 Post subject: Re: Joseki tesuji puzzle
Post #3 Posted: Tue Feb 16, 2021 6:14 am 
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Yep that's it. :)

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