(;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.])))