(;GM[1]FF[4]AP[glGo:1.4]ST[1] SZ[19]KM[6.5] PW[White]PB[Black]DT[2011-07-07] AB[qb][rb][rc][qf][pf][pe][rg][sg][pd][pc][od][ne]AW[qc][rd][qd][qe][se][sf][rf][pb][pa][oc][nd][nc][nb][na]C[White to win the corner unconditionally.] (;W[sb] ;B[sc] (;W[ra] ;B[sa] ;W[qa]C[RIGHT Well done! Black cannot approach. White will wait until there are no ko threats left on the board, and then play t18 followed by t16.]) (;W[qa] ;B[ra]C[Seki]) (;W[sa] ;B[ra])) (;W[sc] ;B[sb] (;W[qa] ;B[sd]C[Two-step ko for white.]) (;W[ra] ;B[sd]C[Two-step ko for White.]) (;W[sa] ;B[sd]C[Two-step ko for White.])) (;W[ra] ;B[qa] (;W[sc] ;B[sa]C[Seki]) (;W[sb] ;B[sa]C[Ko])) (;W[qa] ;B[sd] ;W[sc] ;B[sb]C[Ko]) (;W[sa] ;B[sd] ;W[sc] ;B[sb]C[Ko]))