(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2] RU[Japanese]SZ[9]KM[6.50] PW[Blanc]PB[Noir]AW[cc][bd][cd][dd][ce][de][ee][fe][he][ef][gf][if][cg][gg][ch][dh][eh][gh][di][gi]AB[db][dc][ed][fd][gd][hd][be][ge][bf][cf][df][ff][bg][dg][eg][fg][fh][ei][fi]LB[ha:Y][ia:N][bf:?]C[Can White kill the black group on B4? Play on Y(es) or N(o) to start.]PL[B] (;B[ia] ;W[bh]C[Let's see how you can defend you group now.] (;B[ah] ;W[ag] (;B[af] ;W[bi] (;B[cb] ;W[ad] ;B[ac] (;W[bb]C[CHOICE] (;B[ba]C[ White cannot do anything against the black group.RIGHT]) (;B[ab] ;W[ba]C[Seki ! a strange one, but seki anyway.RIGHT])) (;W[ab]C[CHOICE] ;B[bb] ;W[bc]C[ White cannot do anything against the black group.RIGHT])) (;B[ad] ;W[ac] ;B[cb] ;W[ae]C[And now, where to find your ko-threat ? :p])) (;B[bi] ;W[ai]C[And now, where to find your ko-threat ? :p ... Next move, play at A5 to capture or connect and capture later. You lose.])) (;B[cb] ;W[ad] (;B[ac] ;W[bb] (;B[ae] ;W[bc] (;B[ba] ;W[ab] (;B[ca] ;W[ag]C[You lose.]) (;B[ah] ;W[ag]C[You lose.])) (;B[ah] ;W[ag]C[You lose.])) (;B[ba] ;W[ag]C[You lose.]) (;B[ah] ;W[ag] (;B[af] ;W[bi] ;B[ba]C[ White cannot do anything against the black group.RIGHT]) (;B[bi]CR[bi] ;W[ai]CR[ai] ;B[bc]CR[bc] ;W[ab]CR[ab] ;B[ah]CR[ah] ;W[ec]CR[ec] ;B[ci]CR[ci]C[RIGHT White could not do anything against the the middle black group.]))) (;B[ah] ;W[ag] ;B[af] ;W[ae]C[You lose.])) (;B[ad] ;W[ae] ;B[af] ;W[ac])) (;B[ha]C[White cannot do anything against the black group.]))