tj86430 wrote:Could someone more knowledgeable comment the upper right corner (move 201->)?
This turned into a kind of 10,000 year ko.
$$B 10,000 year ko
$$ ---------------------------------------
$$ | . . . . . . . . . . . X X X O . 3 5 6 |
$$ | . . . . . O X . . . . X O O O O . 4 . |
$$ | . . . . . O X . X X X . X O X O O O 2 |
$$ | . . . O . O X X O X O X . X X X X O 1 |
$$ | O X O . . . O O O O O X . . . . X X 9 |
$$ | . O O O X O O . . O O O X . . X O . . |
$$ | . X O X O O X . O X X O X . . . . . . |
$$ | . X O X O X O O O X O O X . . . . X X |
$$ | . . X X O X X X O X X X X . . X . X O |
$$ | . . X , X . . X O X O O X X . , X O O |
$$ | . . . . . . . X O O O . O O X X X O X |
$$ | . . . . X X X X O X O O O . O X O O . |
$$ | . . . X O O O X O X X O X O O O . . . |
$$ | . . X O . O X X O O X X X X . O O . . |
$$ | . . X O . . O O O X . . . O . X O O . |
$$ | . . X O . . . . O X X X X X . X X O 8 |
$$ | . . X O . X . O . O O X O X . . . X O |
$$ | . X O O . . . . . . O O O X . . . X 7 |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
- Click Here To Show Diagram Code
[go]$$B 10,000 year ko
$$ ---------------------------------------
$$ | . . . . . . . . . . . X X X O . 3 5 6 |
$$ | . . . . . O X . . . . X O O O O . 4 . |
$$ | . . . . . O X . X X X . X O X O O O 2 |
$$ | . . . O . O X X O X O X . X X X X O 1 |
$$ | O X O . . . O O O O O X . . . . X X 9 |
$$ | . O O O X O O . . O O O X . . X O . . |
$$ | . X O X O O X . O X X O X . . . . . . |
$$ | . X O X O X O O O X O O X . . . . X X |
$$ | . . X X O X X X O X X X X . . X . X O |
$$ | . . X , X . . X O X O O X X . , X O O |
$$ | . . . . . . . X O O O . O O X X X O X |
$$ | . . . . X X X X O X O O O . O X O O . |
$$ | . . . X O O O X O X X O X O O O . . . |
$$ | . . X O . O X X O O X X X X . O O . . |
$$ | . . X O . . O O O X . . . O . X O O . |
$$ | . . X O . . . . O X X X X X . X X O 8 |
$$ | . . X O . X . O . O O X O X . . . X O |
$$ | . X O O . . . . . . O O O X . . . X 7 |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

is a mistake, which

capitalized upon.

The result is a 10,000 year ko, which Black should initiate.
Where should

be? There are three plausible candidates.
$$B White replies
$$ ----------------
$$ X X X O . . a . |
$$ X O O O O . b c |
$$ . X O X O O O . |
$$ X . X X X X O 1 |
$$ X . . . . X X . |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |
- Click Here To Show Diagram Code
[go]$$B White replies
$$ ----------------
$$ X X X O . . a . |
$$ X O O O O . b c |
$$ . X O X O O O . |
$$ X . X X X X O 1 |
$$ X . . . . X X . |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |[/go]
Each of "a", "b", and "c" leaves the same count, 6 points for White in the corner.
$$W 2-1
$$ ----------------
$$ X X X O . 8 1 . |
$$ X O O O O 9 6 7 |
$$ . X O X O O O 3 |
$$ X . X X X X O X |
$$ X . . . . X X 4 |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |
- Click Here To Show Diagram Code
[go]$$W 2-1
$$ ----------------
$$ X X X O . 8 1 . |
$$ X O O O O 9 6 7 |
$$ . X O X O O O 3 |
$$ X . X X X X O X |
$$ X . . . . X X 4 |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |[/go]
If White plays on this 2-1 point, later we figure that

-

is sente. Then Black has two ko threats in the corner.
$$W The other 2-1
$$ ----------------
$$ X X X O . 6 7 . |
$$ X O O O O 9 8 1 |
$$ . X O X O O O 3 |
$$ X . X X X X O X |
$$ X . . . . X X 4 |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |
- Click Here To Show Diagram Code
[go]$$W The other 2-1
$$ ----------------
$$ X X X O . 6 7 . |
$$ X O O O O 9 8 1 |
$$ . X O X O O O 3 |
$$ X . X X X X O X |
$$ X . . . . X X 4 |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |[/go]
If White plays on the other 2-1 point, Black also has two ko threats in the corner.
$$W 2-2
$$ ----------------
$$ X X X O . 6 7 . |
$$ X O O O O . 1 . |
$$ . X O X O O O 3 |
$$ X . X X X X O X |
$$ X . . . . X X 4 |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |
- Click Here To Show Diagram Code
[go]$$W 2-2
$$ ----------------
$$ X X X O . 6 7 . |
$$ X O O O O . 1 . |
$$ . X O X O O O 3 |
$$ X . X X X X O X |
$$ X . . . . X X 4 |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |[/go]
But if White plays on the 2-2 point, Black has only one ko threat in the corner. The 2-2 is the spot to play.

----
Earlier
$$B Inside play
$$ ----------------
$$ X X X O . 1 3 . |
$$ X O O O O . 2 5 |
$$ . X O X O O O . |
$$ X . X X X X O 4 |
$$ X . . . . X X . |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |
- Click Here To Show Diagram Code
[go]$$B Inside play
$$ ----------------
$$ X X X O . 1 3 . |
$$ X O O O O . 2 5 |
$$ . X O X O O O . |
$$ X . X X X X O 4 |
$$ X . . . . X X . |
$$ O X . . X O . . |
$$ O X . . . . . . |
$$ O X . . . . X X |
$$ X X . . X . X O |[/go]

would have been technically better as in this diagram. The result is seki. (White can make a ko, but that is normally bad.)