(;
AB[np][op][pp][qp][oq][or][rq][sq]
AW[ql][qn][mo][no][oo][ro][rp][mp][lq][nq][nr][qq][pr]
(;
B[qr]
C[The obvious defense, but Black's shape has a problem.];
W[os]
TR[qq]
C[Now Black's problem is clear - the marked point is a false eye.]
(;
B[pq]
C[For example ...];
W[ps]
C[With a false eye and a dead square shape in the corner, Black dies.]
)
    (;
    B[ps]
    C[Throw-ins often work in similar positions, but ...];
    W[qs]
    (;
    B[pq];W[rs]
    C[Black only has a ko.]
    )
        (;
        B[rs];W[rr]
        )
    )
    (;
    B[rs]
    C[Better, but ...];
    W[ps];B[sr];W[pq]
    C[Black loses half the group to live with only 2 points.]
    )
)
    (;
    B[rs]
    C[An interesting try, but ...];
    W[rr];B[qr];W[qs];B[pq];W[qr];B[sr]
    C[... ko.  White takes 1st.]
    )
    (;
    B[qs]
    C[Another interesting try, but ...];
    W[ps];B[os];W[rr];B[pq];W[qr];B[rs];W[ss];B[rs];W[sp]
    C[... Black runs out of moves.]
    )
    (;
    B[pq]
    C[A very peculiar move - that works best!];
    W[os]
    C[White's best sequence follows, but ...];
    B[ps];W[qs];B[rs];W[rr];B[sr]
    C[... Black hangs on by a thread to live outright and save all the stones in double ko!]
    )
)

