EVENT
BOARDSIZE 19
SETUP W K17 O17 O15 
SETUP B D16 H17 M17 Q16 Q14 
MARK @@K15 1@O15
COM
Reference Diagram to Problem 4. Black to play.  

Instead of @ in Problem 4, White jumps out from the other side
with 1.
ENDCOM
B 1 L16
USER
CORERECT ANSWER
ENDUSER
COM
Correct Answer.

Black plays 2, attacking the white stone on the left.
<=
ENDCOM
EVENT
BOARDSIZE 19
SETUP W K17 O16 
SETUP B D16 F17 Q15 R17 R10 
COM
Reference Diagram to Problem 11. White to play.  

Where should White play in the upper right corner ?
ENDCOM
W 1 Q17
MARK A@M17
COM
Correct Answer.

To appreciate just how big Black's invasion at A is, suppose
White played 1 ...
ENDCOM
B 2 Q16
W 3 P17
COM
... and 3 first.
ENDCOM
B 4 R18
W 5 O14
COM
After 5, White has a large territory at the top and she is also
threatening to invade the right side.
<=
ENDCOM
EVENT
BOARDSIZE 19
SETUP W K17 M18 N17 O17 M16 
SETUP B D16 H17 L18 N18 M17 Q16 Q14 
MARK 1@N18 3@L18 2@N17 4@M16 @@O18
COM
Reference Diagram to Problem 16. Black to play.  

White 4 instead of @ is the usual variation.  

ENDCOM
B 1 L17
USER
CORERECT ANSWER
ENDUSER
COM
Correct Answer.
ENDCOM
W 2 L16
B 3 K18
W 4 O18
COM
After White 4 and ...  
ENDCOM
B 5 Q18
MARK A@O15
COM
... Black 5 are exchanged, White must think about completing
her shape with a move at A.  <= 
ENDCOM
EVENT
BOARDSIZE 19
SETUP W K17 O15 P15 P17 Q16 
SETUP B D16 H17 M15 M17 Q15 R16 P14 
MARK 1@Q16 @@Q14
COM
Reference Diagram to Problem 17. Black to play.  

White plays peacefully at 1 instead of @.
ENDCOM
B 1 R15
USER
CORERECT ANSWER
ENDUSER
COM
Correct Answer.
ENDCOM
W 2 O14
B 3 P13
W 4 R17
B 5 S17
W 6 R18
MARK A@K15
COM
It would be prudent for White to settle her stones with the moves
to 6. Black can now aim at A, again dominating the top left.
<=
ENDCOM
EVENT
BOARDSIZE 19
SETUP W O17 Q18 L17 
SETUP B D16 G17 R17 Q16 Q14 
MARK 3@L17 2@R17 1@Q18
COM
Reference Diagram to Problem 34.

Sliding to 1 and extending two spaces to 3 is joseki. If White
wants to extend three spaces, she should not exchange 1 for Black
2.
<=
ENDCOM
EVENT
BOARDSIZE 19
SETUP W C14 H17 H15 O17 
SETUP B D16 F16 F14 L16 Q16 Q14 R10 
MARK @@L14
COM
Reference Diagram to Problem 47. White to play.  

What is White's alternative to the capping move of @ ?
ENDCOM
W 1 O15
USER
CORERECT ANSWER
ENDUSER
COM
Correct Answer.

Since the capping move is unreasonable, White has no choice but
to jump to 1, ...
ENDCOM
B 2 L14
COM
... letting Black take the key point of 2.
<=
ENDCOM
EVENT
BOARDSIZE 19
SETUP W C14 H17 H15 O17 O15 R12 L15 
SETUP B D16 F16 F14 Q16 Q14 L17 P13 
MARK \t@L17 3@L15 2@P13 1@O15
COM
Reference Diagram to Problem 50.

In this situation, if Black invaded deeply with the marked stone,
Black has no effective moves to rescue this stone after White
3.
<=
ENDCOM
EVENT
BOARDSIZE 19
SETUP W C16 E17 H17 C12 R10 M15 
SETUP B C10 K17 K15 Q17 R17 R15 M17 
MARK 1@M15 2@M17
COM
Reference Diagram to Problem 75. 

Erasing Black's moyo with White 1 is also bad. Black solidifies
the territory at the top with 2.
<=
ENDCOM
EVENT
BOARDSIZE 19
SETUP W D17 C15 C12 K17 N17 
SETUP B C10 R17 R14 P17 H17 
MARK 1@H17 \t@P17
COM
Reference Diagram to Problem 157.

If Black had the marked stone in place, then an invasion at 1might
be playable, since it attacks the two white stones on the right.
<= 
ENDCOM
EVENT
BOARDSIZE 19
SETUP W C17 D16 F16 L17 O17 Q18 K4 D4 F4 P9 
SETUP B R17 Q16 Q14 R9 Q3 M4 C6 C11 C14 B16 Q11 
MARK 2@Q11 1@P9
COM
Reference Diagram to Problem 165. White to play.  

Black 2 in answer to the white capping move of 1 is possible,
too. What should White do now ?
ENDCOM
W 1 R3
MARK \t@Q11
USER
CORERECT ANSWER
ENDUSER
COM
Correct Answer.

Responding the white cap with the marked black stone is also
possible, but now White 1 ...
ENDCOM
B 2 R4
W 3 Q4
COM
... and 3 become powerful moves.
ENDCOM
B 4 P3
COM
If Black plays 6, Black has fallen into White's trap.
ENDCOM
W 5 R8
B 6 Q8
W 7 Q9
B 8 R10
COM
The sequence continues up to Black 8, and then ...
ENDCOM
W 9 R7
B 10 P8
W 11 R5
B 12 S4
W 13 P4
B 14 R2
W 15 S5
B 16 S3
W 17 O8
MARK \t@R4 \t@Q8
COM
... the moves to White 17 follow. White has driven a wedge of
territory between the two marked black stones. This is a big
turnaround from before White invaded; it was Black who then dominated
this side of the board.
<=
ENDCOM