Today I watched an exiciting game on KGS between twoeye(7d) and iKGS5dan(6d, black), the sixth one in a series.
The position after b213 is. The question is who wins in the upper right corner.

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . X . . . . . . . O X . b a B . . . |
$$ | . X . X O . . . O O X . O O X O . . . |
$$ | . . X O O . . O O X X X . . X O . . . |
$$ | . . X X O . . O X O O X X X X O . . . |
$$ | . . . . . . X O X O O O O . X O O . . |
$$ | . . X X . . O X X X O O X X X X O . . |
$$ | . X O X . X X O X X X O O O O X X . . |
$$ | X O O . X O . O O O X X . . . O X . . |
$$ | . X . O X X . O X X . X O O O . O . . |
$$ | X . X O O O O O X , X . X X O , O . . |
$$ | . X O O . O X O O X . . . X X O O X . |
$$ | . X X X X O X . O . . X X O X X O . . |
$$ | . . X O O X X . . O . X O O X O O . . |
$$ | . . . O X X . X X . O O . O O X X X . |
$$ | . . O . O X X O . X X O O . . . . X . |
$$ | . O O , O X . O X O O O . O O O O X . |
$$ | . O X X X O X X X . . X O X . X X O . |
$$ | . X . O O O O O X . . O X X . . X O . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Next W exchanged a for b and then the game proceeded as follows

Click Here To Show Diagram Code

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

Soon W lost the semeai and the game. I think the initial exchange is the losing move. See the hidden part.Correct?
edit: corrected a typo

Quite interesting
I'm at work right now can't really read this till the end but what say you against this?

_________________
The similarity between Go and computing is the seemingly infinite number of possibilities.

Your quick glance is probably worth more than my extensive glance. But it seems your refutation is correct.
So the verdict is that black lives after his initial hane at move 213 and has a won game.

Maybe not. If White starts on the other side with the hane of , can Black kill White without a ko? Something like the below looks complex. What is the correct outcome in the corner? Also, if both sides live, who wins the game?

Click Here To Show Diagram Code

[go]$$Bc
$$ ----------------------+
$$ . . O X . 1 . X . 9 . |
$$ O O X . O O X O 5 6 . |
$$ O X X X . . X O 7 8 . |
$$ X O O X X X X O . . . |
$$ X O O O O . X O O . 0 |
$$ X X O O X X X X O 4 . |
$$ X X X O O O O X X 2 . |
$$ O O X X . . . O X 3 . |
$$ X X . X O O O . O . . |
$$ X , X . X X O , O . . |
$$ O X . . . X X O O X . |
$$ O . . X X O X X O . . |[/go]

_________________
Dave Sigaty
"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21

Why throw in at all? Why not block at R19?

Go is so easy. Just block as Herman proposes and Black is finished, isn't he?

Some gossips about iKGS5dan(6d, black). He appeared some 3 days ago on kgs and played about 80 games since then. He favours to start as black with two 6-4 moves and a move in the center. Rumours are that he changes his nick as soon as his bad habits gets known. Such as. Unprepared dans he tries to play with too high unfavourable handicaps. If his opponent claims a misclick we get:

iKgs5Dan [7d]: no undo when 3s/move
yakito [1k]:

iKgs5Dan [6d]: no undo
MrHyphen [5k]: lolz

Often he claims a misclick and gets away with it. If the opponent refuses he escapes.

hellabryan [?]: if it's a misclick w wouldnt undo then he just got a taste of his own medicine from a few games ago