EVENT
BOARDSIZE 19
SETUP W K17 L16 O17 O16 
SETUP B D16 H17 M17 P17 Q16 Q14 
MARK 2@L16 1@M17
COM
Problem 28. Black to play.  

White counters Black's invasion with the diagonal move of 2.
How does Black respond ? 
ENDCOM
B 1 M16
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black plays 1 and ...
ENDCOM
W 2 M15
B 3 N15
COM
... cuts with 3.
ENDCOM
  VAR
  B 3 L15
  COM
  Variation.

  Black can also cut at 3 here.
  ENDCOM
  W 4 K15
  B 5 L14
  W 6 N15
  B 7 M18
  MARK 6@N15 4@K15
  COM
  After White plays 4 and 6, Black again descends to 7.
  <=
  ENDCOM
  ENDVAR
W 4 N16
B 5 M18
MARK B@O18 A@K18
COM
Black 5 is a steady move, threatening to link up his stones at
A or B.
<=
ENDCOM
  VAR
  B 5 L15
  COM
  Black 5 here is also possible.
  <=
  ENDCOM
  ENDVAR