(;
GM[1]
SZ[19]
AW[md][nc][oc][pc][qb]
AB[jp][jd][pj][dj][dp][pd][pp][dd][od][nd][ne][qc]
TR[qb]
C[Problem 3. Black to play.  

How should Black respond to the marked white stone ? ]
(;B[rb]
TE[2]
C[Correct Answer.  

The two-step hane of Black 1 is an effective move in this position because of the cutting points in White's group. ]
;W[rc]
C[If White goes after the black stone in the corner with 2 ... ]
;B[qd]
(;W[ra]
C[... and 4, ... ]
;B[mc]
C[... Black cuts with 5. ]
;W[sb]
C[If White captures with 6, ... ]
;B[lc]
C[... Black extends to 7 and gets massive thickness in the center. <= ]
)
(;W[pb]
C[If White plays 4 here, ... ]
;B[rd]
C[... then capturing a stone with the atari of 5 is big for Black. <= ]
))
(;B[rc]
LB[rb:@][qd:A]
C[How the game continued.  

Being afraid of the cut at A, Black descended to 1. This was a passive move. Depending on later developments, White @ might be a strong move, so Black's position on the right cannot be considered thick. ]
;W[cn]
C[In the meantime, White played 2 ... ]
;B[fp];W[dg]
LB[qd:A]
C[... and 4 on the left side leaving the cut at A as aji. <= ]
)
)