(;
AB[pn][qn][qo][qp][pq][pr]
AW[no][np][po][pp][qq][qr][nr]
C[Black plays.]
(;
B[rq]
C[Looks obvious, but fails.];
W[rr];B[sr];W[rp];B[rs];W[sq];B[qs]
C[Not a pleasant ko for Black.]
)
    (;
    B[qs]
    C[Also fails.];
    W[rs];B[rr];W[ps];B[rq];W[or];B[qs]
    C[At least Black doesn't risk losing the marked stones with a ko, but ...]
    TR[pq][pr];
    W[qr]
    C[... Black's corner territory is next to nothing.]
    )
    (;
    B[rr]
    C[Famous tesuji.];
    W[rq];B[qs]
    C[Black captures the corner stones!]
    )
)

