(;GM[1]FF[4]SZ[19]
GN[Black gives white an extra ko threat]
PC[http://senseis.xmp.net/?L1Group/Discussion]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?L1Group/Discussion

Black gives white an extra ko threat]
PL[B]

AB[cb][cc][bd][cd][be]
AW[db][eb][dc][dd][ce][ee][bf][cf]

;B[ab]C[B1]MN[1]
;W[ba]C[W2]MN[2]
;B[ca]C[B3]MN[3]
;W[ae]C[W4]MN[4]
;B[ad]C[B5]MN[5]
;W[bb]C[W6]MN[6]
;B[bc]C[B7]MN[7]
;W[da]C[W8]MN[8]

;
)
