(;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.])))