(;
AB[pr][pq][ps][oq][nq][mr][lq][kr][qq]
AW[qr][pp][oo][no][mp][mq][lo][jp][jr][ir][qp][jo][rr][rq]
C[White plays.]
(;
W[ns]
C[Obvious ... and incorrect!]
(;
B[nr]
C[An innocent-looking forcing move that saves the group.];
W[os]
C[White must take away Black's 2nd eye, but ...];
B[ks]
C[... now Black has room for a seki.];
W[kq];B[lr];W[ms]
C[And to add insult to injury a seki, to prevent Black from living with territory, is gote for White.]
)
    (;
    B[ks]
    C[Bad timing.  Black returns the favor.];
    W[nr]
    (;
    B[kq];W[ms];B[ls]
    C[White has a favorable 2 step ko.]
    )
        (;
        B[ms]
        C[Black cannot make a 2nd eye this way.];
        W[lr];B[ls];W[kq]
        )
    )
)
    (;
    W[ks]
    C[The only move!]
    (;
    B[ns]
    C[Black has 2 eyes, correct?];
    W[ls]
    C[A difficult-to-spot killing move!];
    B[or];W[ms]
    C[Black dies.]
    )
        (;
        B[ls];W[ns]
        LB[lr:A]
        C[Black has a false eye at A, and a bulky five shape!]
        (;
        B[js];W[kq]
        )
            (;
            B[kq];W[js]
            )
        )
    )
)

