(;
AB[rn][no][po][qo][op][nq][mr][rr][sr][qs]
AW[qp][rp][sp][pq][qq][or][os]
C[Black plays.

White clearly has more outside liberties than Black's inside group.  To avoid giving White a seki, Black would seem to need to somehow force a dead shape on the inside.]
(;
B[qr]
C[This move creates an eye, but does not yet leave a dead shape.];
W[rs]
C[White jumps at the chance to throw in here to ruin the bulky-5 dead shape.  Now White only needs enough outside liberties to capture the inside stones for a living shape.

White needs 4 inside moves to atari Black's stones, while Black needs 6 moves to fill the outside liberties.

So ...];
B[oq];W[pr];B[nr];W[rq];B[ro];W[ps];B[pp];W[sq]
C[White has just enough liberties to live.]
)
    (;
    B[oq]
    C[Filling an outside liberty here first is bad timing.]
    (;
    W[rs]
    C[White can still throw in here.];
    B[pr]
    C[One possible continuation, but ...];
    W[qr];B[ss];W[ps];B[nr]
    C[... Black only has a bad ko.]
    )
        (;
        W[qr]
        C[Note that carelessly playing here is a mistake.];
        B[rs];W[rq];B[nr];W[sq];B[ns];W[pr]
        C[Now White has to fill in an internal liberty to avoid the snapback.];
        B[ss]
        C[Black creates a dead shape.]
        )
    )
    (;
    B[rs]
    C[Correct!  Black makes an eye with a bulky-5 shape.];
    W[qr]
    C[Otherwise, Black plays here next.];
    B[oq]
    TR[or][os]
    LB[pr:A]
    C[An important move to create a liberty shortage for the marked stones with a false eye at A.];
    W[rq];B[nr];W[sq];B[ns];W[pr];B[ss]
    C[White dies.]
    )
)

