EVENT BOARDSIZE 19 SETUP W D16 C15 F16 K16 O17 Q8 Q6 R6 D4 D6 C9 SETUP B Q16 Q14 Q10 R5 Q4 O4 K4 F3 C14 D14 C11 E11 MARK \t@Q8 \t@Q6 \t@R6 COM Problem 43. Black to play. How should Black attack the marked white stones in the lower right ? ENDCOM B 1 R9 USER CORRECT ANSWER ENDUSER COM Correct Answer. Black 1 is severe because it attacks White's base. ENDCOM VAR B 1 R10 MARK @@R9 COM A solid move. Making an iron pillar with Black 1 is a solid move. Its appeal is that it prevents a white counterattack at A or an invasion at B. However, it lacks the attacking force of Black 1 in the Correct Answer (@), and, as such, is a bit passive. <= ENDCOM ENDVAR VAR B 1 N7 COM Failure. Attacking with Black 1 doesn't press White hard enough. ENDCOM W 2 R10 COM White can secure her stones ... ENDCOM B 3 R11 W 4 R9 B 5 Q11 W 6 S5 B 7 S4 W 8 S6 MARK C@H3 B@M3 A@R3 COM ... with the sequence to 8. Black ends in sente, but with so many weak points - at A, B, and C - he won't be able to defend all of them. <= ENDCOM ENDVAR W 2 N7 COM If White jumps out to 2, ... ENDCOM VAR W 2 R8 COM Variation. If White makes a base for her stones with 2, ... ENDCOM B 3 O9 COM ... Black can attack at 3 ... ENDCOM W 4 N7 B 5 N5 COM ... and 5. ENDCOM W 6 O8 COM White must exchange 6 ... ENDCOM B 7 N9 MARK D@M3 C@R3 B@S5 A@S7 E@Q12 COM ... for 7 to maintain the link to the outside. If White gets into trouble in the center, she can make two eyes by playing at A, but Black B would then become sente and White can no longer invade at C. If White can secure her stones, she can aim to invade at D or E, but Black's strategy will be to try and strengthen these defects while attacking the white stones. <= ENDCOM ENDVAR B 3 N5 MARK B@R3 A@O9 COM ... Black can defend at 3 or attack at A. He need not worry about an invasion at B because White must first secure her stones in the center before she can contemplate such an invasion. <= ENDCOM