1

In josekipedia, they state that this exchange is a mistake

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See http://www.josekipedia.com/#path:pdttpfqcpcqdqepbobrbpaqaqb for the full sequence they argue with.

But, I think that their argument is wrong! Why would white not follow making this shape, which is alive?

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It is true that there are perhaps better possibilities for white's second move (in terms of points, not life & death), but the followup of the "mistake" and argument they present doesn't seem right for the above reason. Or did I miss something?

EDIT: actually, this shape works in the following joseki: http://josekipedia.com/#path:qettodqcpcqdperb

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  • Given your proposed S18, black would just play Q18 and while white is alive, she'd be confined completely and black's outside would have no weaknesses at all (and end in sente, of course). Compare to joseki, in which white gets more points and black gets a weakness (cut) on the outside. – mafu Jan 25 '15 at 4:30
5

Maybe I'm missing something, but I don't think that shape is alive.

$$B 
$$ ----------------------------
$$ | . . . . . . . . . . . . . .
$$ | . O 7 1 . . . . . . . . . .
$$ | 4 . O X . . . . . . . . . .
$$ | . 5 O X . . . . . , . . . .
$$ | 6 2 X . . . . . . . . . . .
$$ | . 3 . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . .

7 is atari, so White loses the eye in the corner.

$$B 
$$ ----------------------------
$$ | . . . . . . . . . . . . . .
$$ | . O . 1 . . . . . . . . . .
$$ | 5 . O X . . . . . . . . . .
$$ | . 4 O X . . . . . , . . . .
$$ | . 2 X . . . . . . . . . . .
$$ | . 3 . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . .

This is dead, too.

$$B 
$$ ----------------------------
$$ | . 5 . . . . . . . . . . . .
$$ | 4 O . 1 . . . . . . . . . .
$$ | 3 . O X . . . . . . . . . .
$$ | . 2 O X . . . . . , . . . .
$$ | . . X . . . . . . . . . . .
$$ | . . . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . .

And again.

Update: Turns out I didn't show the trickiest variation. When White plays 4, 5 is hard to find, but it's often a tesuji in this kind of shape.

$$B 
$$ ----------------------------
$$ | . . . . . . . . . . . . . .
$$ | . O . 1 . . . . . . . . . .
$$ | . . O X . . . . . . . . . .
$$ | 4 . O X . . . . . , . . . .
$$ | . 2 X . . . . . . . . . . .
$$ | 5 3 . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . .

I think White is still dead. If he goes this way, 4 is the tesuji:

$$W
$$ ----------------------------
$$ | . 3 2 . . . . . . . . . . .
$$ | 4 O 1 X . . . . . . . . . .
$$ | 5 . O X . . . . . . . . . .
$$ | O 6 O X . . . . . , . . . .
$$ | . O X . . . . . . . . . . .
$$ | X X . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . .

Here he gets a false eye:

$$W
$$ ----------------------------
$$ | . 4 . . . . . . . . . . . .
$$ | 1 O . X . . . . . . . . . .
$$ | . . O X . . . . . . . . . .
$$ | O 3 O X . . . . . , . . . .
$$ | 2 O X . . . . . . . . . . .
$$ | X X . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . .

This way, the throw in still destroys the lower eye.

$$W
$$ ----------------------------
$$ | . 3 . . . . . . . . . . . .
$$ | . O 2 X . . . . . . . . . .
$$ | 1 . O X . . . . . . . . . .
$$ | O 4 O X . . . . . , . . . .
$$ | . O X . . . . . . . . . . .
$$ | X X . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . .
  • OK, good! I was learned this shape by some 7-8k who claimed it to be alive. Thanks for making it cledar! BTW, what rank are you? – Tomas Jan 27 '15 at 19:55
  • I looked into white 2 at 1-4 and couldn't find anything but death there as well. – OmnipotentEntity Feb 2 '15 at 5:01
  • I'm between 1-2d AGA. – TimK Feb 2 '15 at 20:02
  • Tim, what if in the 1st variant of yours white plays 4 one space below, i.e. at 1-4? I cannot find a way how black could kill this. – Tomas Jun 19 '15 at 13:09
0

White hanes at S15, and when Black counter hanes at S14, White plays the key move, Q18. After two hane and connection moves, White lives with T16, ending the sequence.

Black should have haned at S 18 instead of playing 1 (R15), and then connected at R18.That forces White to crawl along the second line to S14, just to live. Black plays R13, and has White running along the "line of defeat."

The corner sequence is "double sente" for either Black or White, and more to the point, relates to the life or death of White.

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