EVENT
BOARDSIZE 19
SETUP W K17 O17 R17 
SETUP B D16 H17 M17 Q16 Q14 
MARK 1@R17
COM
Problem 10. Black to play.  

This time White has switched to the corner with an invasion at
1. How should Black respond ? 
ENDCOM
B 1 Q17
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should let White live in the corner and make a wall on
the outside.
ENDCOM
W 2 Q18
B 3 P18
  VAR
  B 3 R16
  COM
  Variation.

  If the right side is important to Black, he could Black with
  3.
  ENDCOM
  W 4 S18
  B 5 S17
  W 6 R18
  B 7 L16
  COM
  Black ends with sente, so he can now switch to attacking the
  lone white stone at the center top with 7.
  <=
  ENDCOM
  ENDVAR
W 4 R18
B 5 P17
W 6 S15
COM
White's two stones at the top are outnumbered, so Black should
easily make profit there.
<=
ENDCOM