(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[White]PB[Black]AW[oa][lb][mb][nb][oc][od][pd][qd][sd][re][rf][rg]AB[pa][ob][pb][rb][pc][qc][rc][rd]LB[oa:1][pa:2]C[It's late yose. Black answered 1 with 2. What can white do?]PL[W]
(;W[ra]CR[ra]
;B[sc]CR[sc]
(;W[qa]CR[qa]
;B[sa]CR[sa]
;W[sb]CR[sb]
;B[se]CR[se]
(;W[na]CR[na]
;B[sa]CR[sa]C[RIGHT White has to win ko twice to kill this group. Even if he loses the ko, he should get ample compensation with the ko threat.])
(;W[sa]CR[sa]
;B[na]CR[na]LB[mg:T]C[Play tenuki at T.]
;W[mg]CR[mg]
;B[qb]CR[qb]
;W[ra]CR[ra]
;B[sa]CR[sa]
;W[sb]CR[sb]
;B[qa]CR[qa]C[Black is alive.])
(;W[sf]CR[sf]
;B[na]CR[na]
(;W[sd]CR[sd]
;B[sa]CR[sa]C[Black is alive in double ko.])
(;W[sa]CR[sa]
;B[qb]CR[qb]
;W[ra]CR[ra]
;B[sa]CR[sa]
;W[sb]CR[sb]
;B[qa]CR[qa]C[Black is alive.])))
(;W[sb]CR[sb]
;B[se]CR[se]
(;W[qa]CR[qa]
;B[na]CR[na]
;W[sa]CR[sa]
;B[qb]CR[qb]
;W[ra]CR[ra]
;B[sa]CR[sa]
;W[sb]CR[sb]
;B[qa]CR[qa]C[Black is alive.])
(;W[na]CR[na]
;B[qa]CR[qa]C[Black is alive])
(;W[sf]CR[sf]
;B[na]CR[na]
;W[qa]CR[qa]
;B[qb]CR[qb]C[Black is alive])))
(;W[sb]CR[sb]
;B[sc]CR[sc]
;W[ra]CR[ra]
;B[se]CR[se]
(;W[na]CR[na]
;B[qa]CR[qa]C[Black is alive.])
(;W[qa]CR[qa]
;B[na]CR[na]
;W[sa]CR[sa]
;B[qb]CR[qb]
;W[ra]CR[ra]
;B[sa]CR[sa]
;W[sb]CR[sb]
;B[qa]CR[qa]TR[oa][sd]C[Black is alive. The two liberties on the outside is what allows black to live.])))