What rank is this tsumego?

Cyan · #1

I've been practising a lot of tsumego but missed this kill in a game. Wondering if I should be able to solve it (meaning I should learn to recognize tsumego in live games) or if it's above my rank?

Black to kill:

kvasir · #2

Maybe it is a hard one?

I tend to divide tsumego into categories depending on if it is a "learning" problem or a "reading" problem. "Learning" problem is something you study, possibly memorize and try to learn something new. "Reading" problem is one that practices reading, because it is tricky or the solution is unexpected. My approach with "reading" problems is to never look at the solution, I'll try but I won't check if it is correct because I don't see that as the point of the exercise. Also if I am not sure I have the solution this is also a practical answer. As you improve some "reading" problems might change categories and become something to study.

If I am not missing something then I'd call this a "reading" problem and wouldn't try to memorize it.

I said I wouldn't look at the solution but that doesn't mean I wouldn't talk about it with anyone

Are you sure black can kill?

Cyan · #3

Seems like this is a hard reading problem, plus the time pressure and the whole board position in a live game makes it even harder. I think black can kill in this way, is this correct?

kvasir · #4

Yeah. That seems to check out.

Cyan · #5

Thanks, I want to put this problem on a tsumego site, but I have no experience in making tsumego. How should I simplify this position into a tsumego?

Cassandra · #6

Cyan wrote:

I've been practising a lot of tsumego but missed this kill in a game. Wondering if I should be able to solve it (meaning I should learn to recognize tsumego in live games) or if it's above my rank?

It will make a decisive difference if you encounter this problem presented as a tsume-go, or in a real game.

If it is a tsume-go, you will be sure that there is a way for Black to kill White's group.
In my experience, this knowledge alone makes it easier in many cases to find the solution.

In a real game, there will still exist some kind of uncertainty, if you did not encounter the key-shapes and key-tesuji of this formation (probably often enough) before.

Thus said, this problem might have been above your rank in a real game, and below (or suitable for) your rank as a genuine tsume-go.

Cassandra · #7

Cyan wrote:

Thanks, I want to put this problem on a tsumego site, but I have no experience in making tsumego. How should I simplify this position into a tsumego?

This positiion is fine as a tsume-go, there is NO need for simplification.

But it would be necessary to identify the key points of shape, as well as some other relevant properties of the stones / strings involved.

Tomorrow at the latest, I will post here an example of my thinking in this regard.
Now it is very late in the evening and I still have to walk my two dogs (one of them is called HONTE

).

Cyan · #8

I added this tsumego to 101weiqi, please take a look and give it a rating!

https://www.101weiqi.com/auditquestion/318584/

Knotwilg · #9

I'm 2d. In a game I would surely go for the kill with :b1:

as in the solution but I would probably screw up at :b3:

because I'd try to falsify the upper eye next, giving White an opportunity to force life at the bottom.

In my practice blog here you will see my latest post featuring a fairly easy tesuji problem which however wasn't trivial for me in the real game. As someone else pointed out, knowing there *is* something, is probably worth a couple of ranks already.

weakwest · **#10**

It's really easy. At most like a 5k 101weiqi problem? No offense but the posters finding it difficult probably have poor life and death skills

Cassandra · **#11**

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . . . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

The space is very open, so the shape analysis is not that trivial.

Click Here To Show Diagram Code: [go]$$W $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . 1 . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

If it was White's turn ...

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O C O X . X . . . | $$ | . . . . . . O O X . . O C O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

White's group has two sure eyes.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O T O X . X . . . | $$ | . . . . . . O O X . T T T O O X . . . | $$ | . . . . . O . . . . . T T . . . . . . | $$ +---------------------------------------+[/go]

A nakade shape inside White's formation.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O Z . . . X . . | $$ | . . O , . X . . . , . M O X . , . . . | $$ | . . . . O O X X X . O . O Z . X . . . | $$ | . . . . . . O O X . . . M O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Two cutting points.

Click Here To Show Diagram Code: [go]$$W $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X 3 X X . . . . . . | $$ | . . . . . . X O . . 3 3 X . . . X . . | $$ | . . O , . X . . . , . . 3 X . , . . . | $$ | . . . . O O X X X . O . 3 X . X . . . | $$ | . . . . . . O O X . . . . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Two White strings with only three liberties.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . T O X . , . . . | $$ | . . . . O O X X X . O T O X . X . . . | $$ | . . . . . . O O X . . T . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

This makes one think about another nakade shape.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . ? . 4 4 X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

White's string at the right has four liberties.
But which a Black stone at the shadowed point would have, too.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . M O O X . . . X . . | $$ | . . O , . X . . . , M . O X . , . . . | $$ | . . . . O O X X X M O . O X . X . . . | $$ | . . . . . . O O X . . . . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

A potential false eye at the top.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . 1 . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

is played at the apparent vital point of the problem.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O 6 O X 7 X . . . | $$ | . . . . . . O O X . 2 X 3 O O X . . . | $$ | . . . . . O . . . . . 8 4 . 5 . . . . | $$ +---------------------------------------+[/go]

Trial continuation at the right.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O O O X X X . . . | $$ | . . . . . . O O X . O C C O O X . . . | $$ | . . . . . O . . . . . O O . X . . . . | $$ +---------------------------------------+[/go]

White got only one eye at the bottom.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . M O O X . . . X . . | $$ | . . O , . X . . . , M . O X . , . . . | $$ | . . . . O O X X X M O O O X X X . . . | $$ | . . . . . . O O X . O . . O O X . . . | $$ | . . . . . O . . . . . O O . X . . . . | $$ +---------------------------------------+[/go]

At the top, there is still the potential false eye.

Click Here To Show Diagram Code: [go]$$Bm9 $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , 1 . O X . , . . . | $$ | . . . . O O X X X . O O O X X X . . . | $$ | . . . . . . O O X b O . . O O X . . . | $$ | . . . . . O . . a 2 . O O . X . . . . | $$ +---------------------------------------+[/go]

But

makes miai of A and B.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . 2 1 . O O X . . . | $$ | . . . . . O . . . 3 . . . . . . . . . | $$ +---------------------------------------+[/go]

Therefore, Black must pre-empt White's life-creating move by playing a diagonal move to :b3:

himself.

White is dead.

Gérard TAILLE · **#12**

Knotwilg wrote:

I'm 2d. In a game I would surely go for the kill with :b1:

as in the solution but I would probably screw up at :b3:

because I'd try to falsify the upper eye next, giving White an opportunity to force life at the bottom.

I do not see where you can play a wrong move:

The logical sequence seems the following

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , 7 . O X . , . . . | $$ | . . . . O O X X X . O 6 O X . X . . . | $$ | . . . . . . O O X . 2 1 3 O O X . . . | $$ | . . . . . O . . . . . . 4 . 5 . . . . | $$ +---------------------------------------+[/go]

and with your suggestion to falsify the upper eye the move :b7:

kills white doesn't it?

BTW in the following position

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X c 2 1 d O O X . . . | $$ | . . . . . O . . a b . . . . . . . . . | $$ +---------------------------------------+[/go]

the moves a, b, c or d seem killing moves but in practice the move "a" is certainly the best one for a yose point of view.

Knotwilg · **#13**

[quote="Gérard TAILLE"][/quote]

See previous answers. Your 4 is thé wrong hane. Then a diagonal decent nu white threatens to connect or make a 2nd eye

Cassandra · **#14**

Gérard TAILLE wrote:

Knotwilg wrote:

I'm 2d. In a game I would surely go for the kill with :b1:

as in the solution but I would probably screw up at :b3:

because I'd try to falsify the upper eye next, giving White an opportunity to force life at the bottom.

I do not see where you can play a wrong move:

The logical sequence seems the following

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , 7 . O X . , . . . | $$ | . . . . O O X X X . O 6 O X . X . . . | $$ | . . . . . . O O X . 2 1 3 O O X . . . | $$ | . . . . . O . . . . . . 4 . 5 . . . . | $$ +---------------------------------------+[/go]

and with your suggestion to falsify the upper eye the move :b7:

kills white doesn't it?

Knotwilg was faster ;-)

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , 7 . O X . , . . . | $$ | . . . . O O X X X . O 6 O X . X . . . | $$ | . . . . . . O O X 0 O X X O O X . . . | $$ | . . . . . O . . 9 8 . 4 . . 5 . . . . | $$ +---------------------------------------+[/go]

must be played from the inside, NOT from the outside.

Gérard TAILLE · **#15**

Cassandra wrote:

Gérard TAILLE wrote:

Knotwilg wrote:

I'm 2d. In a game I would surely go for the kill with :b1:

as in the solution but I would probably screw up at :b3:

because I'd try to falsify the upper eye next, giving White an opportunity to force life at the bottom.

I do not see where you can play a wrong move:

The logical sequence seems the following

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , 7 . O X . , . . . | $$ | . . . . O O X X X . O 6 O X . X . . . | $$ | . . . . . . O O X . 2 1 3 O O X . . . | $$ | . . . . . O . . . . . . 4 . 5 . . . . | $$ +---------------------------------------+[/go]

and with your suggestion to falsify the upper eye the move :b7:

kills white doesn't it?

Knotwilg was faster ;-)

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , 7 . O X . , . . . | $$ | . . . . O O X X X . O 6 O X . X . . . | $$ | . . . . . . O O X 0 O X X O O X . . . | $$ | . . . . . O . . 9 8 . 4 . . 5 . . . . | $$ +---------------------------------------+[/go]

must be played from the inside, NOT from the outside.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . 2 1 3 O O X . . . | $$ | . . . . . O . . . . . . 4 a 5 . . . . | $$ +---------------------------------------+[/go]

When white plays hane on the outside white threatens to make an eye at "a" and the answer :b5:

is natural.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . 2 1 3 O O X . . . | $$ | . . . . . O . . c 5 b 4 . . . . . . . | $$ +---------------------------------------+[/go]

OC, similarly, when white plays hane on the inside white threatens to make an eye at "b" and the answer :b5:

is still natural.
BTW, instead of :b5:

it may be better for black to answer at "c".
I still do not see how white can live.

Cyan · **#16**

Knotwilg wrote:

Gérard TAILLE wrote:

See previous answers. Your 4 is thé wrong hane. Then a diagonal decent nu white threatens to connect or make a 2nd eye

Even with 4 at kosumi white dies.

I've submitted 8 variations of solutions in this link, hope it answers everyone's questions about how black can kill.

https://www.101weiqi.com/auditquestion/318584/

CDavis7M · **#17**

I've started to realize something doing tsumego, especially ones from real games.

There's the rank at which someone can solve the tsumego problem itself.

Then there's the rank at which someone would recognize the situation in game and play corrected, which is about 3 ranks higher than solving.

And then there's the rank at which someone would have played moves to setup the tsumego. Which is what? 6 ranks higher than solving? Of course, ranks are relative so this is just for illustration.

And then there's the rank at which the player reads several variations of which the tsumego and many others are options and they play moves to only incidentally setup the tsumego as a threat but of course neither they nor their opponent will ever let the game to that position.

Of course, in most games you just try something out and stumble into a position. It would be nice if the Go-Fairy could just whisper whether seki or ko count as a correct answer.

Gérard TAILLE · **#18**

CDavis7M wrote:

I've started to realize something doing tsumego, especially ones from real games.

There's the rank at which someone can solve the tsumego problem itself.

Then there's the rank at which someone would recognize the situation in game and play corrected, which is about 3 ranks higher than solving.

And then there's the rank at which someone would have played moves to setup the tsumego. Which is what? 6 ranks higher than solving? Of course, ranks are relative so this is just for illustration.

And then there's the rank at which the player reads several variations of which the tsumego and many others are options and they play moves to only incidentally setup the tsumego as a threat but of course neither they nor their opponent will ever let the game to that position.

Of course, in most games you just try something out and stumble into a position. It would be nice if the Go-Fairy could just whisper whether seki or ko count as a correct answer.

I agree with you, depending of your rank, you will have a different appreciation of a move.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . 1 . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Surely the move :b1:

above is the only move to kill white stones and as such :b1:

is a good move.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . 2 X . O O X . . . | $$ | . . . . . O . . a . . . . . . . . . . | $$ +---------------------------------------+[/go]

What about the answer :w2:

? For a strong player no doubt it is a very bad move. First of all white loses a ko threat and secondly when black answers with "a" white suffers locally a great loss. Each time white adds a move this move is probably a bad move isn't it?

Elom0 · **#19**

Gérard TAILLE wrote:

CDavis7M wrote:

I've started to realize something doing tsumego, especially ones from real games.

There's the rank at which someone can solve the tsumego problem itself.

Then there's the rank at which someone would recognize the situation in game and play corrected, which is about 3 ranks higher than solving.

And then there's the rank at which someone would have played moves to setup the tsumego. Which is what? 6 ranks higher than solving? Of course, ranks are relative so this is just for illustration.

And then there's the rank at which the player reads several variations of which the tsumego and many others are options and they play moves to only incidentally setup the tsumego as a threat but of course neither they nor their opponent will ever let the game to that position.

Of course, in most games you just try something out and stumble into a position. It would be nice if the Go-Fairy could just whisper whether seki or ko count as a correct answer.

I agree with you, depending of your rank, you will have a different appreciation of a move.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . 1 . O O X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Surely the move :b1:

above is the only move to kill white stones and as such :b1:

is a good move.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . 2 X . O O X . . . | $$ | . . . . . O . . a . . . . . . . . . . | $$ +---------------------------------------+[/go]

What about the answer :w2:

? For a strong player no doubt it is a very bad move. First of all white loses a ko threat and secondly when black answers with "a" white suffers locally a great loss. Each time white adds a move this move is probably a bad move isn't it?

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . X . O O X . . . | $$ | . . . . . O . . . 2 . . . . . . . . . | $$ +---------------------------------------+[/go]

Also, what happens if white plays the knights move?

Gérard TAILLE · **#20**

Elom0 wrote:

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . X . O O X . . . | $$ | . . . . . O . . . 2 . . . . . . . . . | $$ +---------------------------------------+[/go]

Also, what happens if white plays the knights move?

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . . . . . . . . X . . . . . . . . | $$ | . . . . . . . X X X O X X . . . . . . | $$ | . . . . . . X O . . O O X . . . X . . | $$ | . . O , . X . . . , . . O X . , . . . | $$ | . . . . O O X X X . O . O X . X . . . | $$ | . . . . . . O O X . . X . O O X . . . | $$ | . . . . . O . . 3 2 . . . . . . . . . | $$ +---------------------------------------+[/go]

What is your idea? If white is unconditionnaly dead then this exchange :w2:

is in practice very bad for white.

What rank is this tsumego?

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