(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[9]KM[0.00]
PW[White]PB[Black]AB[ef][eg][fh][gh]
;B[ad]
;W[af]
;B[bd]
;W[bf]
;B[cd]
;W[be]
;B[dd]
;W[ce]
;B[ae]
;W[df]
;B[de]
;W[dg]
;B[ee]
;W[eh]C[start position]
(;B[ch]C[Variation 1: Ko]
;W[bh]
;B[cg]
;W[dh]
;B[bg]
;W[ag]
;B[bi]
;W[ah]
;B[di]
;W[ei]
;B[fi])
(;B[bh]C[Variation 2: Another ko]
;W[ch]
;B[bg]
;W[bi]
;B[ag]
;W[cf]
;B[ei]
;W[ah])
(;B[bg]C[Variation 3: The answer!]
;W[ch]
;B[ei]
(;W[bh]
;B[ag]
;W[cf]
;B[dh]
;W[cg]
;B[ci])
(;W[di]C[Another failure for white]
;B[ag]
;W[cf]
;B[cg]
;W[dh]
;B[bh]
;W[fi]
;B[bi])
(;W[cg]C[Another failure for W]
;B[ag]
;W[cf]
;B[dh]
;W[ci]
;B[bh])
(;W[dh]C[Sub problem: What does B do?]
;B[cf]
;W[cg]
;B[ag]
;W[cf]
(;B[bh]C[Correct solution - W dies]
;W[bi]
;B[ah])
(;B[di]C[Incorrect for B: W gets ko.]
;W[bh]
;B[bi]
;W[ai]
;B[ah]
;W[ai]
;B[ah]
;W[ci]
;B[fi]
;W[ai]))))
