A question on a joseki refutation

gostudent · #1

Click Here To Show Diagram Code: [go]$$W 4-4 approach one space pincer enter 3-3 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 3 4 . 1 . 2 . . . . . . . . . . . | $$ | . . 5 X . . . . . , . . . . . , . . . | $$ | . . b a . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

It is well known that in the above sequence, black needs to play at (a) instead of (b), because of the following sequence:

Click Here To Show Diagram Code: [go]$$W White will capture black stones $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 2 . . . . . . . . . . . . . . . | $$ | . . O X . O . X . . . . . . . . . . . | $$ | . . O X 5 . . . . , . . . . . , . . . | $$ | . . X 3 6 0 . . . . . . . . . . . . . | $$ | . . 4 7 9 . . . . . . . . . . . . . . | $$ | . . . 8 . . . . . . . . . . . . . . . |[/go]

followed by

Click Here To Show Diagram Code: [go]$$W Will White capture black stones? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X 2 O 3 X . . . . . . . . . . . | $$ | . . O X O 4 . . . , . . . . . , . . . | $$ | . . X O X X 5 . . . . . . . . . . . . | $$ | . . X O O 1 . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

However, it seems that black can create a capturing race by

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

At this point, the corner white group has four liberties, and the black group has six liberties. So white need to do something in the corner. One possibility is:

Click Here To Show Diagram Code: [go]$$W Ko fight? $$ --------------------------------------- $$ | . 5 4 . X . . . . . . . . . . . . . . | $$ | 6 . O X . X O . . . . . . . . . . . . | $$ | 7 . O X X O O X . . . . . . . . . . . | $$ | 3 . O X . X . . . , . . . . . , . . . | $$ | . 1 X O X X O . . . . . . . . . . . . | $$ | 8 2 X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

which, according to the discussion in this thread viewtopic.php?f=4&t=11505, the corner white group cannot make two eyes. In fact, black group seems to have a higher number of liberties, though I may have mis-counted.

Do I miss something obvious that white can do to kill the black stones easily? Thanks.

Bki · #2

If White has the ladder, then this can work ( :b6:

connect).

Click Here To Show Diagram Code: [go]$$W Will White capture black stones? $$ --------------------------------------- $$ | . . . 3 . . . . . . . . . . . . . . . | $$ | . . O X 5 . . . . . . . . . . . . . . | $$ | . . O X 2 O . X . . . . . . . . . . . | $$ | . . O X O 4 7 . . , . . . . . , . . . | $$ | . . X O X X . . . . . . . . . . . . . | $$ | . . X O O 1 . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

I'm pretty sure there is a better way though, just, it's late right now so...

Edit :

:w1:

in your last diagram is wrong. Instead :

Click Here To Show Diagram Code: [go]$$W Capturing race $$ --------------------------------------- $$ | . . 1 . X . . . . . . . . . . . . . . | $$ | . . O X . X O . . . . . . . . . . . . | $$ | 5 3 O X X O O X . . . . . . . . . . . | $$ | . 2 O X . X . . . , . . . . . , . . . | $$ | . 4 X O X X O . . . . . . . . . . . . | $$ | . . X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

Big eye, you win the capturing race (if :b2:

at

, then

at

and you have even more space.

Instead, if B attempt to set up a ko, this :w5:

thwart him (changing the order for :w5:

and

is also possible, but that's a needless sacrifice.

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

Edit 2: As an aside :

Quote:

Click Here To Show Diagram Code: [go]$$W Ko fight? $$ --------------------------------------- $$ | . 5 4 . X . . . . . . . . . . . . . . | $$ | 6 . O X . X O . . . . . . . . . . . . | $$ | 7 . O X X O O X . . . . . . . . . . . | $$ | 3 . O X . X . . . , . . . . . , . . . | $$ | . 1 X O X X O . . . . . . . . . . . . | $$ | 8 2 X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

The J-group is sente (though I guess it might be a ko if the surrounding group isn't alive). :w3:

is wrong, and should be one line below (descent rather than tiger mouth). Then you can avoid the ko, because Black must give you a four space big eye, and so you win once again the capturing race.

Edit : there are also possibility of winning by double ko, I think. But it's getting very late around here.

EdLee · #3

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

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

Quote:

It is well known that in the above sequence, black needs to play at (a) instead of (b), because of the following sequence:

There are many sequences and variations; interesting to study.

B can play the hane in some special cases. Good to study.

gostudent · #4

Thank you for the input. Some thoughts:

Bki wrote:

Click Here To Show Diagram Code: [go]$$W Capturing race $$ --------------------------------------- $$ | . . 1 . X . . . . . . . . . . . . . . | $$ | . . O X . X O . . . . . . . . . . . . | $$ | 5 3 O X X O O X . . . . . . . . . . . | $$ | . 2 O X . X . . . , . . . . . , . . . | $$ | . 4 X O X X O . . . . . . . . . . . . | $$ | . . X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

Despite the big eyes, it looks like that white will lose the capturing race, because the outside liberty difference is too much:

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

or

Click Here To Show Diagram Code: [go]$$B Capturing race. at $$ --------------------------------------- $$ | 8 4 O 7 X . 2 . . . . . . . . . . . . | $$ | 5 3 O X . X O . . . . . . . . . . . . | $$ | O O O X X O O X . . . . . . . . . . . | $$ | 1 X O X . X 6 . . , . . . . . , . . . | $$ | . X X O X X O . . . . . . . . . . . . | $$ | . . X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

This may be a bit better:

Click Here To Show Diagram Code: [go]$$W Capturing race $$ --------------------------------------- $$ | . 6 1 . X 9 7 . . . . . . . . . . . . | $$ | 5 . O X . X O . . . . . . . . . . . . | $$ | 0 3 O X X O O X . . . . . . . . . . . | $$ | 8 2 O X . X . . . , . . . . . , . . . | $$ | . 4 X O X X O . . . . . . . . . . . . | $$ | . . X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

followed by

Click Here To Show Diagram Code: [go]$$W Capturing race. take ko. $$ --------------------------------------- $$ | 3 X O 5 X O O . . . . . . . . . . . . | $$ | O 2 O X 1 X O . . . . . . . . . . . . | $$ | X O O X X O O X . . . . . . . . . . . | $$ | X X O X . X . . . , . . . . . , . . . | $$ | . X X O X X O . . . . . . . . . . . . | $$ | . . X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

and black cannot connect. It will be difficult to read this out in actual game (at least for my level), though.

EdLee wrote:

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

It looks like that black can connect to the outside stone by playing at (a).

EdLee · #5

Hi GoStudent,

If W has this ladder, W can consider :wc:

descend and this var:

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

If W does not have the above ladder, W can consider the hane :w1:

sequence and fight:

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

There may be situations where W wants to play this, despite the ladder:

Click Here To Show Diagram Code: [go]$$W at (a) $$ ----------------------- $$ | . . . 7 . . . . . . . $$ | . . O X 8 4 6 . . . . $$ | . . O X 2 O . X . . . $$ | a . O X O 5 . . . , . $$ | . 9 X O B B 3 . . . . $$ | . 0 X O O 1 . . . . . $$ | . . . X . . . . . . . $$ | . . . . . . . . . . .[/go]

Or, start a fight:

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

In your OP, you said "because of this sequence..." (Abridged & emphasis added
As you can see, it's not just 1, 2, or 3 sequences.
There are many sequences and variations starting with the 3rd line B hane.
Interesting and good to study.

Uberdude · #6

This old chestnut again! So it's worth saying that hane rather than descent is usually the correct punishment for black's cheeky hane. See extensive discussion from viewtopic.php?p=161723#p161723.

Also in these variations under discussion now, even if white has a better move earlier that result of corner death is good for white if you can find time to cut on the left as it's super thickness.

Bki · #7

gostudent wrote:

Thank you for the input. Some thoughts:

Bki wrote:

Click Here To Show Diagram Code: [go]$$W Capturing race $$ --------------------------------------- $$ | . . 1 . X . . . . . . . . . . . . . . | $$ | . . O X . X O . . . . . . . . . . . . | $$ | 5 3 O X X O O X . . . . . . . . . . . | $$ | . 2 O X . X . . . , . . . . . , . . . | $$ | . 4 X O X X O . . . . . . . . . . . . | $$ | . . X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

Despite the big eyes, it looks like that white will lose the capturing race, because the outside liberty difference is too much:

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

Hum...

Yeah, it doesn't work because :b5:

is atari. I will blame that on the late time at which I answered. but, like I said in an edit :

Click Here To Show Diagram Code: [go]$$W White win $$ --------------------------------------- $$ | . 5 4 . X . . . . . . . . . . . . . . | $$ | 6 . O X . X O . . . . . . . . . . . . | $$ | 7 8 O X X O O X . . . . . . . . . . . | $$ | . 9 O X . X . . . , . . . . . , . . . | $$ | 3 1 X O X X O . . . . . . . . . . . . | $$ | . 2 X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

Click Here To Show Diagram Code: [go]$$B White win (continuation) connect. $$ --------------------------------------- $$ | 4 O X . X . . . . . . . . . . . . . . | $$ | X 2 O X . X O . . . . . . . . . . . . | $$ | O X O X X O O X . . . . . . . . . . . | $$ | 1 O O X . X . . . , . . . . . , . . . | $$ | O O X O X X O . . . . . . . . . . . . | $$ | . X X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

Click Here To Show Diagram Code: [go]$$B White win by double ko. $$ --------------------------------------- $$ | O O X . X 4 2 . . . . . . . . . . . . | $$ | . O O X 6 X O . . . . . . . . . . . . | $$ | 1 . O X X O O X . . . . . . . . . . . | $$ | 5 O O X . X . . . , . . . . . , . . . | $$ | O O X O X X O . . . . . . . . . . . . | $$ | 3 X X O O O . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . |[/go]

A question on a joseki refutation

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