(;
GM[1]
SZ[19]
AW[gp][qf][pm][ld][pg][mg]
AB[jp][jd][pj][dj][dp][pd][pp][dd][nd][dn][nq][pf][nj]
LB[pf:1][pg:2]
TR[ld]
C[Problem 6. Black to play.  

After White played the marked stone in Problem 2, Black attached with 1. How should he answer White 2 ? ]
(;B[qe]
TE[2]
C[Correct Answer.  

Blocking with Black 1 secures the corner. ]
;W[of]
C[White has no choice but to atari with 2, ... ]
;B[pe];W[qg]
C[... then connect with 4. ]
;B[qi]
C[Black strengthens his position with 5 on the right side, preventing White from making a base there and forcing her to make eyes in the center. Next, ... ]
;W[dg]
LB[dg:??]
C[... (White ?? is necessary here to get "Black to move") ... ]
;B[me]
C[...  Black is threatening to split White in two with the sequence from Black 7 ... ]
;W[le];B[mf];W[lf];B[ng]
C[... to Black 11.  <= ]
)
(;B[of]
C[How the game continued.  

The extension of Black 1 enabled White to make a wall ... ]
;W[og];B[qe];W[qg];B[nf];W[ng]
LB[qc:A]
C[... with the sequence to 6. Whereas White's stones were previously thin, they were now thick. Moreover, Black ended this skirmish with bad aji at A. See Problem 10 for the continuation.  <= ]
)
)