(;CA[gb2312]AB[nf][ne][mg][le][ld][og][kb][jd][ic][hc][rc][lc][pb][ob][nb][sf][rg]
[qg][qi][ql][ni][gb]AW[nh][mh][lh][kf][ie][ge][mc][mb][lb][gc][cd][dc][fc][rb][re]
[rf][qf][pf][qd][pd][od][oe][sg][nd][nc][ng]C[White first to live. This problem contains many steps, but all necessary and can be calculated.

Note\: Problem extracted from #117 in 囲碁発陽論
]
AP[MultiGo:4.4.4]SZ[19]AB[qb]MULTIGOGM[1]
;W[pg]C[White 1 is the only move];B[ph]C[White has two options, both works as ko]
(;W[of];B[oh];W[me];B[mf];W[lf];B[md];W[lg];B[me];W[se];B[ra];W[jb]C[After White 13, this became a white vs. black life and death problem. ]
;B[ka];W[sh];B[ri]C[White 11 and 15 all aimed to extend its liberty];W[kc];B[jc]
;W[ja];B[kd];W[la];B[kc];W[ib];B[ia];W[ha];B[hb];W[ia];B[eb];W[fb];B[fa];W[da];B[na]
;W[db];B[rh];W[ea];B[ga];W[ia];B[rd];W[hd];B[sd];W[je];B[si];W[id];B[ma];W[ke];B[oc]
;W[ib];B[pc];W[ja];B[qc];W[jb];B[ha];W[ia];B[sf];W[sg];B[sh];W[ja];B[qe];W[ib];B[jb]
;W[ia];B[sf]C[Ko, very heavy for black, thus better for white.])
(;W[oh];B[of];W[se];B[ra];W[pi]C[Black has two options, R12 or S12]
(;B[qh]C[If black chooses to connect];W[qj];B[pj];W[ri];B[oi];W[rh];B[pi];W[qk]
;B[pk];W[rl]C[White can live on the side, bad for black])
(;B[rh];W[qh]C[The only other choice for black is to make a ko, but it's still not in a good shape.])))