Book 1 of the LCH tesjui set is mostly "spot the key point" capturing races, where the continuation is a one-way street. But problem 92 seems to have a lot more variations than anything else in the book. As far as I can tell, there are actually two ways for black to capture the white stones on the left. Does anyone else agree?
$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . X . . . . . . . .
$$ | . O X . . . . . . .
$$ | . O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ ---------------------
[go]$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | 5 X . . . . . . . .
$$ | . O X . . . . . . .
$$ | 2 O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 1 a 3 . . . . . . .
$$ | . 4 . . . . . . . .
$$ ---------------------[/go]
Black only has two liberties and can't really increase them so an atari is the first thing to look at.
at "a" obviously fail because it's the corner, so trying for a ko seems to be white's strongest resistance. increase liberties and threaten to live in the corner which would capture the six white stones, so is forced then win the capturing race
Next some other moves that might be worth exploring but fail :
$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | 7 X . . . . . . . .
$$ | . O X . . . . . . .
$$ | 6 O X . X . . . . .
$$ | 5 O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 4 2 1 8 . . . . . .
$$ | . 3 . . . . . . . .
$$ ---------------------
[go]$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | 7 X . . . . . . . .
$$ | . O X . . . . . . .
$$ | 4 O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 3 1 . 5 6 . . . . .
$$ | . 2 . . . . . . . .
$$ ---------------------[/go]
Being clver and trying to set up a ko ultimately fail
Re: Lee Changho tesuji book 1 problem 92
Posted: Sun Oct 13, 2019 3:56 pm
by xela
Thanks bki, looks good to me. Your very first diagram is the variation diagram from the book (white has a less tricky but more profitable response which is given as the main line). All your failure variations are not in the book, and I agree that they fail. Your very last diagram is given in the book as failure, but I agree with you that it succeeds.
Re: Lee Changho tesuji book 1 problem 92
Posted: Mon Oct 14, 2019 3:52 am
by Bki
By the way, the tesuji-looking in the following is why I thought this second variation failed initially :
$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . X . . . . . . . .
$$ | . O X . . . . . . .
$$ | . O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 2 1 . 5 . . . . . .
$$ | . 3 4 . . . . . . .
$$ ---------------------
[go]$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . X . . . . . . . .
$$ | . O X . . . . . . .
$$ | . O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 2 1 . 5 . . . . . .
$$ | . 3 4 . . . . . . .
$$ ---------------------[/go]
But after , black make an eye and white can't ever capture black. at C2 also obviously fail for the same reason, and anything else fail by simply counting liberties.
Re: Lee Changho tesuji book 1 problem 92
Posted: Mon Oct 14, 2019 4:17 am
by Knotwilg
This is what I saw:
$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | 9 X . . . . . . . .
$$ | . O X . . . . . . .
$$ | 2 O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 1 3 . 5 8 . . . . .
$$ | . 4 6 7 . . . . . .
$$ ---------------------
at "a" obviously fail because it's the corner, so trying for a ko seems to be white's strongest resistance. 
increase liberties and threaten to live in the corner which would capture the six white stones, so 
is forced then 
win the capturing race