(;
GM[1]
SZ[19]
AW[ec][eb][ed][dd][cd][ce][be][ci][dp][dn][jc][mc][qg][oh][oj][qj][ro][qp][qq][qr][pr][np][op][oo][po][nn][gp][hq][jq][jr][kr][kp][lp][lq][mr]
AB[bc][cc][dc][bd][fc][cf][oc][pd][qe][qh][ph][pg][ql][qn][rn][qo][or][oq][pq][pp][nq][mq][mp][mo][lo][no][mn][jo][jp][ho][fq][ir][hr][iq]
TR[oh][oj][qj]
C[Problem 84. Black to play.  

How should Black attack the three marked stones ? ]
(;B[mh]
TE[2]
C[Correct Answer.  

Capping with Black 1 is severe. ]
;W[mj]
C[If White 2, ... ]
;B[ki]
C[... Black continues the attack with the knight's move of 3. ]
;W[nh]
C[White tries to get some play with 4 ... ]
;B[mi];W[nf]
C[... and 6, but ... ]
;B[kd]
C[... Black leans on the White stones at the top with 7 ... ]
;W[pf];B[qf];W[kc];B[md]
C[... and 11. White is in trouble. <= ]
)
(;B[oi]
C[Failure.  

If Black wedges in with 1, ]
;W[nj];B[ni];W[mj];B[mi];W[lj]
LB[mi:5][ni:3]
TR[mc][jc]
C[... White easily escapes with the sequence to 6. The wall Black gets with 3 and 5 is ineffective because it is neutralised by the two marked stones at the top. <= ]
)
)