(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Chinese]SZ[19]KM[7.50]
PW[White]PB[Black]AW[eb][ec][gc][cd][ed][de][bf][cf][df]AB[db][dc][bd][dd][be][ce]
;B[]
;W[bb]
;B[cc]
(;W[bc]
;B[ba]C[This leads to a ko at best.]
(;W[ca]
;B[da]
(;W[cb]
;B[ab])
(;W[aa]
;B[cb]))
(;W[ac]
;B[ad]
;W[ca]
;B[da])
(;W[ab]
;B[ad]
;W[ca]
;B[cb]))
(;W[ba]C[This is the proper killing move.]
(;B[da]
;W[bc]
;B[ac]
;W[ab])
(;B[ca]
;W[bc]
;B[ac]
;W[cb]
;B[da]
;W[ea])
(;B[bc]
;W[da])))
