Another set of 4x4-problems, made last weekend during a go tournament.
Please find the best result for Black!
(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][cc]AB[ca][ab][db][ac][dc][ad][bd]C[Black to play - what's the best he can do?]
(;B[cb]CR[cb]
(;W[cd]CR[cd]
;B[bc]CR[bc]
;W[aa]CR[aa]
;B[bc]CR[bc]C[Black wins by eleven points :) RIGHT])
(;W[bc]CR[bc]
;B[cd]CR[cd]C[White is lost!]))
(;B[cd]CR[cd]
;W[cb]CR[cb]
(;B[bc]CR[bc]
;W[da]CR[da]C[White wins])
(;B[dd]CR[dd]
;W[da]CR[da]C[White connects the ko and wins by one point])
(;B[aa]CR[aa]
;W[da]CR[da]C[White wins]))
(;B[bc]CR[bc]
;W[cb]CR[cb]
;B[cd]CR[cd]
;W[da]CR[da]C[White wins!]))