(;
AB[pc][pe][pj][pk][nm][no][oo][kn][qo][qp][pp][pq][pr]
AW[dd][dp][kp][lq][op][oq][or][po][pn][pm][qn][ol][ok]
C[Black plays.
Source:  "Attack and Defense", Ch. 2,
         Akira Ishida & James Davies, Ishi Press]

(;
B[mk]
C[Correct.
Black strengthens his weak group and weakens White's group.];
W[oj];
B[pi];
W[oi];
B[ph];
W[mi];
B[kj]
)
    (;
    B[oj]
    C[Bad.
Black only pushes White against Black's own weak group.];
    W[mk];
    B[in];
    W[hp]
    C[White makes territory while attacking.];
    B[nj]
    C[This follow up is no good.];
    W[ml]
    LB[ln:a][rm:b][qi:c][rk:d]
    C[And white threatens A.
Worse yet, White B is sente against the Black corner.
White can invade at C and threaten to link up with D.]
    )
    (;
    B[ql]
    C[Only an endgame move.];
    W[mk]
    LB[rm:a][qi:b]
    C[White takes the key point, and still threatens A and
then B.]
    )
)
