(;AP[goproblems]AB[sb]AB[rb]AB[rc]AB[re]AB[qe]AB[pe]AB[oe]AB[nd]AB[nc]AB[nb]AW[ra]AW[sc]AW[sd]AW[rd]AW[qd]AW[pd]AW[pc]AW[pb]AW[pa]C[Kill the white stones. No Seki or Ko.](;B[qb]MA[sb]MA[qb]MA[rc]TR[rb]MA[qc]C[White is dead. Black is a killing shape and can extend into R17 to make a 5 stone killing shape. If the stones are captured, black plays at S18 to create a dead eye space.RIGHT])(;B[sa]C[];W[qb]MA[qa]C[White lives. Black failed to create a killing shape. No ko.];B[qa]C[No KoNOTTHIS])(;B[se]C[];W[qb]C[White lives. Black failed to create a killing shape.])(;B[qc];W[qb]C[White lives. Black failed to create a killing shape.])(;B[qa];W[qb]C[White lives. Black failed to create a killing shape.])(;B[oa];W[qb])(;B[ob];W[qb])(;B[oc];W[qb])(;B[od];W[qb]))