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Question about a tesuji-problem

https://lifein19x19.com/viewtopic.php?t=11973

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Question about a tesuji-problem

Posted: Sat Jun 27, 2015 3:00 pm
by BadukStone
In Lee Changho's Selected Tesuji Problems, I've encountered a tesuji-problem which, I think, has two solutions (a and b):


Black to play
Click Here To Show Diagram Code
[go]$$
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . , . . . . . , |
$$ | . X X O . . . . . . |
$$ | . O X O . . . . . . |
$$ | a . O X O . . . . . |
$$ | . O O X O . . . . . |
$$ | b O X X O . . . . . |
$$ | X O X , O . . . . , |
$$ | . X X O . . . . . . |
$$ | . . O O . . . . . . |
$$ | . . . . . . . . . . |
$$ ---------------------[/go]
'a' was the solution given in the book, and I agree with that, but I think 'b' is also the right move.

My question is whether this problem has two solutions or not.

Re: Question about a tesuji-problem

Posted: Sat Jun 27, 2015 6:40 pm
by Loons
My two cents, in a relatively bad currency:

'b' is, in isolation just worse than 'a' if black later decides to sacrifice.

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 7:02 am
by ez4u
BadukStone wrote:In Lee Changho's Selected Tesuji Problems, I've encountered a tesuji-problem which, I think, has two solutions (a and b):


Black to play
Click Here To Show Diagram Code
[go]$$
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . , . . . . . , |
$$ | . X X O . . . . . . |
$$ | . O X O . . . . . . |
$$ | a . O X O . . . . . |
$$ | . O O X O . . . . . |
$$ | b O X X O . . . . . |
$$ | X O X , O . . . . , |
$$ | . X X O . . . . . . |
$$ | . . O O . . . . . . |
$$ | . . . . . . . . . . |
$$ ---------------------[/go]
'a' was the solution given in the book, and I agree with that, but I think 'b' is also the right move.

My question is whether this problem has two solutions or not.
It appears to have at least 3. :)

Interestingly, the Web Go Board extension that I use took your original asymmetrical 10x11 diagram and turned it into a 10x10 (a previously undiscoverd bug?), changing the problem to the situation below. This appears to have only one solution. What is it?
:study:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | . X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | a . O X O . . . . . |
$$ | . O O X O . . . . . |
$$ | b O X X O . , . . . |
$$ | X O X . O . . . . . |
$$ | . X X O . . . . . . |
$$ | . . O O . . . . . . |
$$ ---------------------[/go]

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 7:11 am
by Knotwilg
Great catch, Dave!

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 8:48 am
by Bill Spight
Very good, Dave! Better problem than the book!

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 9:00 am
by BadukStone
Loons wrote:My two cents, in a relatively bad currency:

'b' is, in isolation just worse than 'a' if black later decides to sacrifice.
Thanks, that makes sense now that I think about it. :scratch:
ez4u wrote:This appears to have only one solution. What is it?
:study:


I think :b1: (b) is wrong this time, because the throw-in at :w2: works now:

( :b5: at :w2: )
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | . X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | . . O X O . . . . . |
$$ | 4 O O X O . . . . . |
$$ | 1 O X X O . , . . . |
$$ | X O X 6 O . . . . . |
$$ | 2 X X O . . . . . . |
$$ | 3 . O O . . . . . . |
$$ ---------------------[/go]

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 9:32 am
by ez4u
BadukStone wrote:
Loons wrote:My two cents, in a relatively bad currency:

'b' is, in isolation just worse than 'a' if black later decides to sacrifice.
Thanks, that makes sense now that I think about it. :scratch:
ez4u wrote:This appears to have only one solution. What is it?
:study:


I think :b1: (b) is wrong this time, because the throw-in at :w2: works now:

( :b5: at :w2: )
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | . X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | . . O X O . . . . . |
$$ | 4 O O X O . . . . . |
$$ | 1 O X X O . , . . . |
$$ | X O X 6 O . . . . . |
$$ | 2 X X O . . . . . . |
$$ | 3 . O O . . . . . . |
$$ ---------------------[/go]
You are on the right track! So what is the right answer?

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 10:31 am
by BadukStone
So I believe that :b1: must be at the same spot as in the book:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | . X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | 1 . O X O . . . . . |
$$ | 7 O O X O . . . . . |
$$ | 3 O X X O . , . . . |
$$ | X O X 4 O . . . . . |
$$ | 5 X X O . . . . . . |
$$ | 6 2 O O . . . . . . |
$$ ---------------------[/go]

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 12:49 pm
by SoDesuNe
Click Here To Show Diagram Code
[go]$$Bc Same problem as before?
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | . X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | 1 . O X O . . . . . |
$$ | . O O X O . . . . . |
$$ | . O X X O . , . . . |
$$ | X O X . O . . . . . |
$$ | 2 X X O . . . . . . |
$$ | . . O O . . . . . . |
$$ ---------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc Increasing liberties
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | 5 X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | 2 . O X O . . . . . |
$$ | 4 O O X O . . . . . |
$$ | 3 O X X O . , . . . |
$$ | X O X . O . . . . . |
$$ | 1 X X O . . . . . . |
$$ | . . O O . . . . . . |
$$ ---------------------[/go]

Re: Question about a tesuji-problem

Posted: Sun Jun 28, 2015 1:36 pm
by BadukStone
SoDesuNe wrote:
Click Here To Show Diagram Code
[go]$$Bc Same problem as before?
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | . X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | 1 . O X O . . . . . |
$$ | . O O X O . . . . . |
$$ | . O X X O . , . . . |
$$ | X O X . O . . . . . |
$$ | 2 X X O . . . . . . |
$$ | . . O O . . . . . . |
$$ ---------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc Increasing liberties
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | 5 X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | 2 . O X O . . . . . |
$$ | 4 O O X O . . . . . |
$$ | 3 O X X O . , . . . |
$$ | X O X . O . . . . . |
$$ | 1 X X O . . . . . . |
$$ | . . O O . . . . . . |
$$ ---------------------[/go]
You're right, I overlooked this variation. :-?
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ | . . X . . . . . . . |
$$ | . . . . . . . . . . |
$$ | . X X O . . . . . . |
$$ | . O X O . . , . . . |
$$ | 1 . O X O . . . . . |
$$ | 5 O O X O . . . . . |
$$ | . O X X O . , . . . |
$$ | X O X 6 O . . . . . |
$$ | 2 X X O . . . . . . |
$$ | 3 4 O O . . . . . . |
$$ ---------------------[/go]
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