(;
AB[qm][rn][mo][no][oo][po][qo][mp][mq][op][rp][lr][nr][pr]
AW[np][nq][qp][qq][sp][oq][or][rq]
C[Black plays.]
(;
B[pq]
C[Capturing 4 stones is big, but ...];
W[ro]
C[... after White makes an eye here, Black has a problem eliminating the 2nd eye.]
(;
B[rr]
C[The obvious attack.];
W[qr];B[qs];W[rs];B[ss];W[sr]
C[White has a ko for saving the remaining stones.]
)
    (;
    B[rs];W[rr];B[sr];W[qs];B[qr]
    C[Again, White has a ko.]
    )
)
    (;
    B[ro]
    C[Taking away White's eye here doesn't work either.];
    W[pq];B[os];W[ps];B[qs];W[rs]
    (;
    B[rr];W[qr];B[ss];W[sr];B[sq];W[ps];B[so];W[ns];B[mr]
    )
        (;
        B[ps];W[qr];B[sr];W[ns]
        C[Capturing with atari lets White lives.]
        )
    )
    (;
    B[ps]
    C[This funny-looking move works.]
    (;
    W[ro];B[rs]
    C[Now Black has enough liberties to deny White a ko in the corner.];
    W[sr];B[rr];W[qr];B[qs];W[ns];B[pq]
    )
        (;
        W[pq];B[os];W[ro];B[rs]
        C[White dies.]
        )
    )
)

