Help with this puzzle, around 1d level?

[Niall]

I've been going through the second set of problems that come with the GoGrinder App on Android. In general they're difficult and I can't always understand all the subtleties. I created this account to start discussion about some of these problems.

Problem 1: Black (X) to play, presumably trying to live in the corner. I cannot see what is wrong with the move labeled 1 in the diagram (or attached .sgf).

$$B
$$ ------------------+
$$ . . . O . . . . . |
$$ . O . X X O O 1 . |
$$ . O . . X . X X . |
$$ . . O . . , . . . |
$$ . . . O . . O O . |
$$ . . . . O O . . . |
$$ . . . . . . . . . |

Click Here To Show Diagram Code

[go]$$B
$$ ------------------+
$$ . . . O . . . . . |
$$ . O . X X O O 1 . |
$$ . O . . X . X X . |
$$ . . O . . , . . . |
$$ . . . O . . O O . |
$$ . . . . O O . . . |
$$ . . . . . . . . . |[/go]

(Thanks to hiddema.nl/diagrammer/ for helping me make the image)

[Niall]

q11 from KGS has supplied an answer.

White threatens to connect, and then aims to make a bulky five.

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

Click Here To Show Diagram Code

[go]$$B
$$ ------------------+
$$ . . . O 3 2 . . . |
$$ . O . X X O O 1 . |
$$ . O . . X . X X 4 |
$$ . . O . . , . . . |
$$ . . . O . . O O . |
$$ . . . . O O . . . |
$$ . . . . . . . . . |[/go]

If black tries to resist by blocking the corner white continues like this:

$$B
$$ ------------------+
$$ . . . O X O 8 6 . |
$$ . O . X X O O X 5 |
$$ . O . . X 7 X X O |
$$ . . O . . , . . . |
$$ . . . O . . O O . |
$$ . . . . O O . . . |
$$ . . . . . . . . . |

Click Here To Show Diagram Code

[go]$$B
$$ ------------------+
$$ . . . O X O 8 6 . |
$$ . O . X X O O X 5 |
$$ . O . . X 7 X X O |
$$ . . O . . , . . . |
$$ . . . O . . O O . |
$$ . . . . O O . . . |
$$ . . . . . . . . . |[/go]

If black tries to capture the three stones to make better shape, white will make a square.

$$B
$$ ------------------+
$$ . . . O X O 6 8 . |
$$ . O . X X O O X 7 |
$$ . O . . X 5 X X O |
$$ . . O . . , . . . |
$$ . . . O . . O O . |
$$ . . . . O O . . . |
$$ . . . . . . . . . |

Click Here To Show Diagram Code

[go]$$B
$$ ------------------+
$$ . . . O X O 6 8 . |
$$ . O . X X O O X 7 |
$$ . O . . X 5 X X O |
$$ . . O . . , . . . |
$$ . . . O . . O O . |
$$ . . . . O O . . . |
$$ . . . . . . . . . |[/go]

[Uberdude]

This is http://senseis.xmp.net/?XuanxuanQijingProblem17