(;SZ[19]AW[bp][co][do][dp][eq]C[What can Black gain here?]AB[cp][bo][bn][cm][en][el][fp][fq][hq]
(;B[dr];W[cq];B[er];W[br]
(;B[aq]C[RIGHT Black kills white.])
(;B[dq];W[aq]C[White lives
]))
(;B[cq];W[bq];B[cr];W[br];B[er];W[dr]C[White catches it.])
(;B[bq];W[cq];B[ap];W[br];B[ar];W[bs];B[dr];W[er];B[fr];W[ds];B[cr];W[aq]C[Ko]))