(;AW[pb]AW[pc]AW[pd]AW[rd]AW[pe]AW[qe]AB[nb]AB[ob]AB[nd]AB[od]AB[qd]AB[oe]AB[re]AB[pf]AW[``]AB[rf]AB[rg]AB[pg]PW[White]PB[Black]
(;B[rc]AB[rg];W[qc]C[]
(;B[rb];W[sd]
(;B[se];W[qb];B[sc]C[RIGHT])
(;B[sc];W[ra]
(;B[se];W[qd]
(;B[sb]C[RIGHT])
(;B[qb];W[sb]C[ko])
(;B[oc];W[sb]C[ko])
(;B[pa];W[sb]
(;B[qa];W[qb])
(;B[sa]C[Ko])))
(;B[sb];W[qb]))
(;B[ra];W[qb]
(;B[sb]C[RIGHT])
(;B[sc];W[sb]))
(;B[pa];W[qa]
(;B[sc];W[sb];B[se];W[qd];B[sa]C[RIGHT])
(;B[se];W[sb];B[sc];W[qd];B[sa]C[RIGHT])))
(;B[sd];W[rb]
(;B[qd];W[sb]
(;B[pa];W[rd]C[ko])
(;B[rd];W[qa]C[w is alive!]))
(;B[sc];W[sb])))
(;B[sd];W[rc];B[rb];W[sb];B[qb];W[qc];B[pa];W[ra])
(;B[ra];W[rb]
(;B[pa];W[qa];B[qb];W[qc]C[ko])
(;B[sb]
(;W[sc];B[qb];W[qc];B[rc]C[ko])
(;W[qc]
(;B[sd];W[qa]
(;B[sc];W[rc])
(;B[rc];W[sc]C[Now if b takes the ko at s17, wt19 and he is alive in double ko.]))
(;B[pa];W[sc]
(;B[qa];W[qb])
(;B[qb];W[qa]C[Now if b takes at r18, wt19 and he is alive in double ko]))))
(;B[rc];W[qc])
(;B[qa];W[pa];B[sd];W[rc]C[alive]))
(;B[rb];W[rc];B[qb];W[qa]
(;B[qc];W[sb])
(;B[ra];W[pa];B[sd];W[qc];B[sc];W[sb])
(;B[sb];W[qc])
(;B[sc];W[sd])
(;B[sd];W[sb]))
(;B[sc];W[rc];B[rb];W[sb]
(;B[sa];W[sd];B[qb];W[qa];B[qc];W[sb])
(;B[qb];W[qa];B[sa];W[sd];B[qc];W[sb]C[ko, white takes first]))
(;B[pa];W[rb];B[ra];W[qc];B[sc];W[qa];B[qb];W[sb];B[sd];W[qa]C[Ko]))