(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2] RU[Japanese]SZ[9]KM[0.00] PB[Noir]AW[cc][dc][ec][cd][fd][gd][ce][ee][ge][cf][ef][gf][bg][cg][fg][gg][bh][gh][bi][fi][gi]AB[fc][gc][hc][dd][ed][hd][de][he][df][hf][dg][eg][hg][ch][dh][fh][hh][ci][ei][hi] (;B[ff]C[Forced, else] (;W[eh]C[else...] ;B[fe] ;W[di] ;B[eb]C[Not a ko threat, but...] (;W[ef]C[forced for the same reason: ] ;B[ei] ;W[ee] ;B[fh] ;W[db]C[And so on] ;B[ff] ;W[eh] ;B[fe] ;W[di] ;B[fb] ;W[ef] ;B[ei] ;W[ee] ;B[fh] ;W[ea] ;B[ff] ;W[eh] ;B[fe] ;W[di] ;B[fa] ;W[ef] ;B[ei] ;W[ee] ;B[fh] ;W[da] ;B[ff] ;W[eh] ;B[fe] ;W[di]C[Now, we enter the real complications. If Black passes] (;B[] ;W[ef] ;B[ei] ;W[ee] (;B[fh]C[this move becomes illegal, as the position was already seen at move 30l. Therefore a) With Japanese rulles, the game ends (mushobu, it is void and must be replayed) , so White had better pass immadiately (at move 36) , winning on the board (but Japanese pros don't seem to agree on this result) b) With AGA rules : Black *must* play elsewhere (superko rule), and loses immadiately (see next variation), which explains variations at move 35 c) if the superko rule is modified (the Bill Spight proposal), it becomes a true infinite repetition, and probably will be counted as mushobu]) (;B[bb] ;W[di])) (;B[hb] ;W[ef] ;B[ei] ;W[ee] ;B[fh] ;W[bc] ;B[ff] ;W[eh] ;B[fe] ;W[di] ;B[ha]C[etc. This line of play leads to Black failure, as she will have to fill her own eyes long before White does.But...]) (;B[bb] ;W[ef] ;B[ei] ;W[ee] ;B[fh] ;W[bc] ;B[ff] ;W[eh] ;B[fe] ;W[di] ;B[ab]C[This other line of play is completely unclear. I let the reader try to solve it (it is called a pass fight), but be warned that the present theory (and of course the players' experience) is probably much too incomplete to get a definitive conclusion...] (;W[ac]C[I dont show the cycle any longer (but it must still be played at *each* outside move, of course)] ;B[ae] ;W[be] ;B[ad] ;W[af] ;B[ah] ;W[bd] ;B[ae] ;W[ad] ;B[ag] ;W[ai] ;B[ag] ;W[ah] ;B[cb] ;W[ca] ;B[hb] ;W[ba] ;B[ha] ;W[aa] ;B[bb] ;W[cb] ;B[gb] ;W[ab] ;B[ga] ;W[bb] ;B[ia] ;W[bf] ;B[ic]C[Just for the fun, to show that if White dont mimic Black, he loses heavily]) (;W[hb]C[I dont show the cycle any longer (but it must still be played at *each* outside move, of course)] ;B[ac] ;W[ad] ;B[ib] ;W[ha] ;B[ae] ;W[bd] ;B[af] ;W[if] ;B[ie] ;W[ic] ;B[id] ;W[ag] ;B[ah] ;W[ba] ;B[cb] ;W[ca] ;B[ig] ;W[aa] ;B[ab] ;W[bb] ;B[gb] ;W[bf] ;B[ga] ;W[be] ;B[ae] ;W[ac] ;B[ia] ;W[hb] ;B[ha] ;W[ih] ;B[ii] ;W[af] ;B[hb] ;W[ai]C[Here, White wins (by only two moves)]))) (;W[db] ;B[ei] ;W[fb] ;B[fh])) (;W[fe] ;B[ff])) (;B[eb] ;W[eh] ;B[db] ;W[di]))