(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2] RU[Japanese]SZ[4]KM[0.00] PW[Weiß]PB[Schwarz]AW[cc][dc][cd]AB[aa][ab][cb][db][ac][ad][bd]C[White to play - what's the best he can do?]PL[W] (;W[bb]CR[bb] ;B[ba]CR[ba] (;W[ca]CR[ca]C[After setting up this double snapback, White wins! RIGHT]) (;W[bc]CR[bc] ;B[dd]CR[dd]C[Uh-oh.....])) (;W[bc]CR[bc] ;B[bb]CR[bb]C[Black wins]) (;W[ba]CR[ba] (;B[ca]CR[ca]C[Black wins]) (;B[bb]CR[bb] ;W[ca]CR[ca] ;B[da]CR[da] ;W[ca]CR[ca] ;B[ba]CR[ba]C[Seki! Black wins by three points only, but B B3 was a mistake.])))