Problem from Graded go problems vol 2

paK0 · #1

Hi, I need some help, I can't figure this out for the life of me.

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

1 is the given book move, but how do you defend against 2, I can only get iffy results at best?

Thanks for your help.

schawipp · #2

I assume the task is to defend the black corner?

Since the connection between the w stones is weak, I would try as follows...

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

White cannot enter the corner much further. A possible continuation is

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

After that, w still needs to protect against "a" and is left with a heavy group.

EDIT: Instead of 7, black can possibly play at "a" immediately. White can capture two black stones, but his whole groups seems to die.

paK0 · #3

Ok, thanks for that.

Since it was given as the best move I though there would be a more severe punishment upon white coming in further, so I kept trying to kill some of the white stones.

Shawn Ligocki · #4

I also just worked through this problem and don't understand it. The problem just asks to find the best white response to :b1:

.

The book explains the solution like this:

Click Here To Show Diagram Code: [go]$$B Correct answer \nBlack 1 is the correct response. If White 2, Black stops White's intrusion with 3. $$ | . . . , . . . . . , . . $$ | . . . O . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . O . O . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X X . X . . X , . . $$ | . . . . . . . 1 . . O . $$ | . . . . . . 3 2 O . . . $$ | . . . . . . . . . . . . $$ -------------------------[/go]

Click Here To Show Diagram Code: [go]$$B Wrong Answer \nThe responses a-d are all inferior to the correct answer. $$ | . . . , . . . . . , . . $$ | . . . O . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . O . O . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X X . X . . X , . . $$ | . . . . . . c . d . O . $$ | . . . . . . b a O . . . $$ | . . . . . . . . . . . . $$ -------------------------[/go]

I thought that b would be the best way to stop white, because I was also worried about the black response paKO posted. Any explanation for why the shoulder hit is better than the one-point approach?

Ortho · #5

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

Now what for W?

schawipp · #6

Shawn Ligocki wrote:

Click Here To Show Diagram Code: [go]$$B Wrong Answer \nThe responses a-d are all inferior to the correct answer. $$ | . . . , . . . . . , . . $$ | . . . O . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . O . O . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X X . X . . X , . . $$ | . . . . . . c . d . O . $$ | . . . . . . b a O . . . $$ | . . . . . . . . . . . . $$ -------------------------[/go]

I thought that b would be the best way to stop white, because I was also worried about the black response paKO posted. Any explanation for why the shoulder hit is better than the one-point approach?

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

After

, white can occupy the Elephant's eye at :w2:

which threatens to cut off the marked black stone or further reduce the corner. After...

Click Here To Show Diagram Code: [go]$$B $$ | . . . , . . . . . , . . $$ | . . . O . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . O . O . . . . . . . $$ | . . . . . 8 7 . . . . . $$ | . . X X . X 6 3 # , . . $$ | . . . . . 5 4 2 a . O . $$ | . . . . . d 1 b O c . . $$ | . . . . . . . . . . . . $$ -------------------------[/go]

... the marked stone is still cut off. Black can try to also cut off white with the a-b-c sequence, but this seems to become quite messy, since w can capture at d and either live at the bottom or re-connect his stones to the right.

@Ortho: Obviously your variation works better than mine given above ;-)

Initially, I was not sure about possible corner aji but I cannot find anything that works for w.

EDIT:

If w has many big ko threats elsewhere, he could at least try the following:

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

With the a-b exchange it's a two-step ko, but if w wins it that would be a big endgame for w lateron. I was also thinking of

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

The white move 4 threatens to play on 5 in sente - thus it forces b to connect in bad shape. If b follows the above given sequence, w can atari at a and connect at b which looks complicated. With a solid corner position I think :b3:

is the best move for b - however in the given situation I am not completely sure. I would appreciate if someone could point out a failsafe variation for b after :w4:

skydyr · #7

Regarding the ko mentioned above:

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

If white just connects, how does black have enough liberties to fight here?

Black has to block on the left and let white take a decent profit, in what seems to be gote-no-sente, if not sente, since white has followups on the left after this:

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

I feel like the problem is asking more about connection and center access in addition to keeping something in the corner, rather than preserving as much of the corner as possible.

Problem from Graded go problems vol 2

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