Hi, I was recently offered Volume 4 from the books "Graded go problems for beginners".
However, I don't understand the answer given by the book for problem #4. I hope someone here can enlighten me

THe first diagram presents the problem, the second one is the answer provided by the book.

Click Here To Show Diagram Code

[go]$$c Problem.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . O . . . . . . . . . . . |
$$ | . X . O O O . . . . . . . . . . . . . |
$$ | . . . O X X X X . . . . . . . . . . . |
$$ | . X X X O O . . X . . X X . . . . . . |
$$ | . O . O X . O . . X . . . . . , . . . |
$$ | . . O O . . . . O O O . X . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$c Answer, the book states that after 5, white has to give up the two stones in atari.
$$ ---------------------------------------
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . O . . . . . . . . . . . |
$$ | . X . O O O . . . . . . . . . . . . . |
$$ | . . . O X X X X . . . . . . . . . . . |
$$ | . X X X O O 5 . X . . X X . . . . . . |
$$ | . O . O Y a O 1 . X . . . . . , . . . |
$$ | . . O O . . 2 3 O O O . X . . . . . . |
$$ | . . . . . . . 4 . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

What I don't understand is that if white plays at a, then the triangled stone is in atari. If I try to go on, I get something which looks like this :

Click Here To Show Diagram Code

[go]$$c cont'd.
$$ ---------------------------------------
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . O . . . . . . . . . . . |
$$ | . X . O O O . . . . . . . . . . . . . |
$$ | . . . O X X X X . . . . . . . . . . . |
$$ | . X X X O O 5 . X . . X X . . . . . . |
$$ | . O . O Y 6 O 1 . X . . . . . , . . . |
$$ | . . O O 7 8 2 3 O O O . X . . . . . . |
$$ | . . . . 9 . 0 4 . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I thought of 9 at 10, but then of course, 7 and the triangled stone are atari, so white seems out of danger. Even better, 9 is useless, isn't it ?
Is there an error somewhere, in the book or in my head ?

White can save the two stones in atari, but black and add up to an even worse loss for white. Black has destroyed way more than 4 points of territory (which was the value of the 2 stones), plus the 3 white stones on the right are captured - that is, they have no way to run away as black has cut them off.

Click Here To Show Diagram Code

[go]$$c
$$ ---------------------------------------
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . O . . . . . . . . . . . |
$$ | . X . O O O . . . . . . . . . . . . . |
$$ | . . . O X X X X . . . . . . . . . . . |
$$ | . X X X O O 5 . X . . X X . . . . . . |
$$ | . O . O Y 6 O 1 . X . . . . . , . . . |
$$ | . . O O 8 . 2 3 O O O . X . . . . . . |
$$ | . . . . . . 7 4 9 . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Ok, thanks, fast reply !
I didn't see things that way, although I went through this variation... But I wanted too much to kill the white groups !

I wouldn't recommend doing that volume of the graded go problems for beginners series unless you a single digit kyu.

ramble:

Good Luck

Yep... As I said before, it was a present, I didn't get to pick the book
But thanks for the heads up