This is a yesterday played KGS game. In the shown position, both players passed and so it was a 4 point win for white (black captured a stone at A). Today, a strong player pointed out that there is some very bad aji inside the white position! Can you see it?!
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
RU[Japanese]SZ[5]KM[0.50]TM[]
AW[ba][bb][cc][cd][ce][de]AB[ca][da][cb][eb][dc][dd][ed][ee]LB[db:A]C[Can Black do anything to avoid defeat?!]
(;B[ad]CR[ad]
(;W[ac]CR[ac]
(;B[be]CR[be]
;W[bc]CR[bc]
(;B[ab]CR[ab]C[This is a common seki and best for both. Black wins by three points! RIGHT CHOICE])
(;B[aa]CR[aa]C[This is a common seki and best for both. Black wins by three points! RIGHT CHOICE]))
(;B[ab]CR[ab]
;W[aa]CR[aa]
;B[be]CR[be]
;W[bc]CR[bc]C[This is a common seki - black wins by three points! RIGHT CHOICE]))
(;W[bd]CR[bd]
(;B[ac]CR[ac]
;W[ab]CR[ab]
;B[be]CR[be]
;W[ae]CR[ae]C[Black has no ko threat CHOICE])
(;B[ab]CR[ab]
;W[bc]CR[bc]
;B[ac]CR[ac]C[This is a seki (white can't start a ko at A1), but since black wins by four points, white lost a point here (answering A2 with A3 is better). RIGHT CHOICE]))
(;W[bc]CR[bc]
(;B[ab]CR[ab]
;W[ac]CR[ac]
;B[be]CR[be]C[This is a common seki - black wins by three points! (Answering B3 at A3 is one point better) RIGHT CHOICE])
(;B[ac]CR[ac]
;W[ab]CR[ab]
;B[be]CR[be]C[Also a commom seki, but since black wins by four points here, white should answer A2 at A3. RIGHT CHOICE])
(;B[be]CR[be]
;W[bd]CR[bd]
;B[ac]CR[ac]
;W[ae]CR[ae]C[Black can't fight this ko :) CHOICE])))
(;B[ac]CR[ac]
;W[ad]CR[ad]
;B[bd]CR[bd]
;W[bc]CR[bc]
;B[ae]CR[ae]
;W[be]CR[be]C[This doesn't work for black])
(;B[bd]CR[bd]
;W[bc]CR[bc]
;B[ac]CR[ac]
;W[ab]CR[ab])
(;B[bc]CR[bc]
;W[bd]CR[bd]
;B[ac]CR[ac]
;W[ad]CR[ad])
(;B[ab]CR[ab]
(;W[ac]CR[ac]
;B[ad]CR[ad]
;W[aa]CR[aa]
;B[be]CR[be]
;W[bc]CR[bc]C[This is a common seki, black wins by three points RIGHT])
(;W[bd]CR[bd]
;B[ad]CR[ad]
;W[bc]CR[bc]
;B[ac]CR[ac]C[Seki! (White can't start a ko at A1) RIGHT CHOICE])
(;W[bc]CR[bc]
;B[ad]CR[ad]
;W[ac]CR[ac]
;B[be]CR[be]C[Seki! RIGHT CHOICE])))