Please find the best result for White!
(japanese rules)
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
RU[Japanese]SZ[4]KM[0.00]
PW[Weiß]PB[Schwarz]AW[ba][bb]AB[ac][bc][bd]C[White to play - what's the best he can do?]PL[W]
(;W[cc]CR[cc]
;B[cd]CR[cd]
(;W[db]CR[db]
(;B[dc]CR[dc]
(;W[cb]CR[cb]
;B[ab]CR[ab]
(;W[aa]CR[aa]
;B[ca]CR[ca]
;W[dd]CR[dd]C[White wins! RIGHT])
(;W[dd]CR[dd]
;B[ca]CR[ca]
(;W[dc]CR[dc]C[Next, White captures at D4 and wins by two points (the 2 prisoners), but he can do better!])
(;W[da]CR[da]
;B[dc]CR[dc]C[Next, Black will connect the ko. White wins by 1 point (2 prisoners against 1) then. That is not good enough!])))
(;W[dd]CR[dd]
;B[cb]CR[cb]
;W[ca]CR[ca]
;B[dc]CR[dc]
;W[cb]CR[cb]
;B[ab]CR[ab]
;W[dd]CR[dd]C[White connects the ko and wins by two points (3 prisoners against 1). But he can do better!]))
(;B[ab]CR[ab]
;W[ca]CR[ca]
;B[dc]CR[dc]
;W[dd]CR[dd]C[White connects the ko and wins.])
(;B[ca]CR[ca]
;W[ab]CR[ab]C[White lives and wins.]))
(;W[cb]CR[cb]
;B[ab]CR[ab]
(;W[dc]CR[dc]
;B[da]CR[da]
(;W[dd]CR[dd]
;B[db]CR[db]
;W[ca]CR[ca]
;B[db]CR[db]
;W[da]CR[da]C[Seki, White wins by three points (the 3 prisoners). This is not best, White can capture all the black stones!])
(;W[aa]CR[aa]
;B[ca]CR[ca]
;W[db]CR[db]
;B[ca]CR[ca]
;W[da]CR[da]C[Seki, White wins by three points (the 3 prisoners). This is not best, White can capture all the black stones!]))
(;W[aa]CR[aa]
;B[da]CR[da]
;W[dc]CR[dc]
;B[db]CR[db]
;W[ca]CR[ca]
;B[db]CR[db]
;W[da]CR[da]C[Seki, White wins by three points (the 3 prisoners). But White can capture all the black stones!])
(;W[dd]CR[dd]
;B[dc]CR[dc]
;W[db]CR[db]
;B[ca]CR[ca]
;W[dd]CR[dd]C[Next, White will connect and then capture at D4. This will be a one point win (two prisoners against 1) - he can do much better!]))
(;W[dc]CR[dc]
;B[ab]CR[ab]
(;W[cb]CR[cb]
;B[da]CR[da]
(;W[aa]CR[aa]
;B[db]CR[db]
;W[ca]CR[ca]
;B[db]CR[db]
;W[da]CR[da]C[Seki, White wins by three poimts (the 3 prisoners). That's not best, White can capture all the black stones!])
(;W[dd]CR[dd]
;B[db]CR[db]
;W[ca]CR[ca]
;B[db]CR[db]
;W[da]CR[da]C[Seki, White wins by three points (the 3 prisoners) That's not best, White can capture all the black stones!]))
(;W[da]CR[da]
;B[cb]CR[cb]
(;W[ca]CR[ca]
;B[aa]CR[aa]
;W[db]CR[db]C[Seki, White wins by one point (the prisoner). He can do much better!])
(;W[db]CR[db]
;B[aa]CR[aa]
;W[ca]CR[ca]C[Seki, White wins by one point (the prisoner). He can do much better!]))
(;W[db]CR[db]
;B[ca]CR[ca]
(;W[cb]CR[cb]
;B[aa]CR[aa]
;W[da]CR[da]C[Seki, White wins by one point (the prisoner). He can do much better!])
(;W[da]CR[da]
;B[aa]CR[aa]
;W[cb]CR[cb]C[Seki, White wins by one point (the prisoner). He can do much better!]))
(;W[ca]CR[ca]
;B[db]CR[db]
(;W[cb]CR[cb]
;B[aa]CR[aa]
;W[da]CR[da]C[Seki, White wins by one point (the prisoner). He can do much better!])
(;W[da]CR[da]
;B[aa]CR[aa]
;W[cb]CR[cb]C[Seki, White wins by one point (the prisoner). He can do much better!]))))
(;W[cb]CR[cb]
;B[cc]CR[cc]
(;W[dc]CR[dc]
;B[ab]CR[ab]
;W[db]CR[db]
;B[ca]CR[ca]C[Now, please capture :)]
(;W[dd]CR[dd]C[NOTTHIS])
(;W[aa]CR[aa]C[NOTTHIS])
(;W[da]CR[da]C[Seki, White wins by one point (the prisoner).]))
(;W[db]CR[db]
;B[dc]CR[dc]
;W[ab]CR[ab]C[Jigo!])))