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Problem from Graded go problems vol 2
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Author:  paK0 [ Thu Dec 26, 2013 10:10 am ]
Post subject:  Problem from Graded go problems vol 2
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.
Author:  schawipp [ Thu Dec 26, 2013 11:04 am ]
Post subject:  Re: Problem from Graded go problems vol 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.
Author:  paK0 [ Thu Dec 26, 2013 11:29 am ]
Post subject:  Re: Problem from Graded go problems vol 2
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.
Author:  Shawn Ligocki [ Sun Dec 29, 2013 2:45 am ]
Post subject:  Re: Problem from Graded go problems vol 2
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?
Author:  Ortho [ Sun Dec 29, 2013 5:40 am ]
Post subject:  Re: Problem from Graded go problems vol 2
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?
Author:  schawipp [ Sun Dec 29, 2013 6:44 am ]
Post subject:  Re: Problem from Graded go problems vol 2
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 :b1:, 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:
Author:  skydyr [ Sun Dec 29, 2013 8:14 pm ]
Post subject:  Re: Problem from Graded go problems vol 2
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.
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