(;AB[ar]AB[br]AB[cq]AB[dq]AB[eq]AW[aq]AW[bq]AW[bp]AW[cp]AW[dp]AW[ep]AW[fp]AW[fq]AW[fr]AB[ds]C[white to kill.]AP[goproblems]
(;W[cs]
(;B[bs]C[CHOICE]
(;W[dr]
(;B[er];W[es]C[black cannot push.RIGHT])
(;B[cr]
(;W[er]C[RIGHT])
(;W[es];B[er])))
(;W[cr];B[dr])
(;W[es];B[dr])
(;W[er];B[dr]))
(;B[cr]C[CHOICE]
(;W[er]
(;B[dr]C[CHOICE];W[bs]C[black dies this way regardless of A3 liberty.RIGHT])
(;B[bs]C[CHOICE];W[dr]C[RIGHT]))
(;W[bs];B[er])
(;W[es];B[bs]))
(;B[er]C[CHOICE];W[cr]C[black cannot approach.RIGHT]))
(;W[es];B[dr])
(;W[er];B[dr])
(;W[dr];B[er]
(;W[cr];B[cs])
(;W[cs];B[cr]))
(;W[cr];B[dr]
(;W[cs];B[bs])
(;W[bs];B[cs]))
(;W[bs];B[cs]
(;W[es];B[dr])
(;W[er];B[dr])
(;W[dr];B[er])
(;W[cr];B[dr])))