It is currently Thu Mar 28, 2024 1:20 pm

All times are UTC - 8 hours [ DST ]




Post new topic Reply to topic  [ 7 posts ] 
Author Message
Offline
 Post subject: Lee Changho tesuji book 1 problem 92
Post #1 Posted: Sun Oct 13, 2019 4:46 am 
Lives in gote

Posts: 580
Location: Adelaide, South Australia
Liked others: 207
Was liked: 264
Rank: Australian 2 dan
GD Posts: 200
One of these problems is not like the others...

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?

Click Here To Show Diagram Code
[go]$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . X . . . . . . . .
$$ | . O X . . . . . . .
$$ | . O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ ---------------------[/go]

Top
 Profile  
 
Offline
 Post subject: Re: Lee Changho tesuji book 1 problem 92
Post #2 Posted: Sun Oct 13, 2019 10:20 am 
Lives with ko

Posts: 218
Liked others: 23
Was liked: 14
Rank: IGS 3k
KGS: Bki
IGS: mlbki
The first thing that appear to work that I see is this :

Click Here To Show Diagram Code
[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.

:b2: at "a" obviously fail because it's the corner, so trying for a ko seems to be white's strongest resistance. :b3: increase liberties and threaten to live in the corner which would capture the six white stones, so :w4: is forced then :b5: win the capturing race


Next some other moves that might be worth exploring but fail :

Click Here To Show Diagram Code
[go]$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . 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]


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



Click Here To Show Diagram Code
[go]$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . X . . . . . . . .
$$ | . O X . . . . . . .
$$ | . O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 6 2 3 1 4 . . . . .
$$ | . 5 . . . . . . . .
$$ ---------------------[/go]


And there's this one which I thought failed but might actually not :

Click Here To Show Diagram Code
[go]$$c Black to play.
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . X . . . . . . . .
$$ | . O X . . . . . . .
$$ | . O X . X . . . . .
$$ | . O O X . . . . . ,
$$ | O X X O O O . . . .
$$ | 2 1 . . . . . . . .
$$ | . 3 . . . . . . . .
$$ ---------------------[/go]

:b3: gains a liberty so black win

Click Here To Show Diagram Code
[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

Top
 Profile  
 
Offline
 Post subject: Re: Lee Changho tesuji book 1 problem 92
Post #3 Posted: Sun Oct 13, 2019 3:56 pm 
Lives in gote

Posts: 580
Location: Adelaide, South Australia
Liked others: 207
Was liked: 264
Rank: Australian 2 dan
GD Posts: 200
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.

Top
 Profile  
 
Offline
 Post subject: Re: Lee Changho tesuji book 1 problem 92
Post #4 Posted: Mon Oct 14, 2019 3:52 am 
Lives with ko

Posts: 218
Liked others: 23
Was liked: 14
Rank: IGS 3k
KGS: Bki
IGS: mlbki
By the way, the tesuji-looking :w4: in the following is why I thought this second variation failed initially :

Click Here To Show Diagram Code
[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 :b5:, black make an eye and white can't ever capture black. :w4: at C2 also obviously fail for the same reason, and anything else fail by simply counting liberties.

Top
 Profile  
 
Offline
 Post subject: Re: Lee Changho tesuji book 1 problem 92
Post #5 Posted: Mon Oct 14, 2019 4:17 am 
Oza
User avatar

Posts: 2408
Location: Ghent, Belgium
Liked others: 359
Was liked: 1019
Rank: KGS 2d OGS 1d Fox 4d
KGS: Artevelde
OGS: Knotwilg
Online playing schedule: UTC 18:00 - 22:00
This is what I saw:

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


Either I have a blind spot, or this line is rejected as White get too many free points

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


This is probably the main line: White forces a capture in sente

Top
 Profile  
 
Offline
 Post subject: Re: Lee Changho tesuji book 1 problem 92
Post #6 Posted: Mon Oct 14, 2019 5:31 am 
Lives in gote

Posts: 580
Location: Adelaide, South Australia
Liked others: 207
Was liked: 264
Rank: Australian 2 dan
GD Posts: 200
Yep, your second diagram is the first answer diagram in the book. I guess it's easier to read out, even if it does let white have a bigger corner.

Top
 Profile  
 
Offline
 Post subject: Re: Lee Changho tesuji book 1 problem 92
Post #7 Posted: Mon Oct 14, 2019 10:18 am 
Gosei
User avatar

Posts: 1810
Liked others: 490
Was liked: 365
Rank: KGS 1-dan
Interesting, that the hane-variation was considered first by so many. My eyes immediately went to make the guzumi : D

_________________
My "guide" to become stronger in Go

Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 

All times are UTC - 8 hours [ DST ]


Who is online

Users browsing this forum: Bing [Bot] and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group