(;
AB[mn][nn][on][mo][po][qo][lp][lq][lr][qp][qq][rq][rr][jr][ms]
AW[no][oo][mp][mq][mr][pp][pq][pr][nq][qr][ls]
C[Black plays.];
B[op]
C[The only move!]
(;
W[np];B[oq]
C[Normally, this kind of move, forcing the opponent to capture stones that already have a liberty shortage, is not useful.  But ...]
(;
W[or];B[ns]
C[... Black can now push into White's eye space.  White cannot make 2 eyes.]
)
    (;
    W[qs]
    C[White can try to expand the eye space, but ...];
    B[os]
    C[... Black's placement creates an awkward situation for White.];
    W[ns];B[or]
    C[White cannot approach from either side.  White dies.]
    )
)
    (;
    W[ns]
    C[Sacrificing the 2 stones doesn't work either.];
    B[or]
    C[Black takes the vital point.];
    W[np];B[oq];W[qs];B[os]
    C[White has the same problem as before.]
    )
    (;
    W[os]
    C[Another promising placement, but ...];
    B[qs]
    C[... Black can simply destroy an eye from the outside.];
    W[np];B[oq];W[ns];B[or]
    C[White has a dead shape.]
    )
)

