(;GM[1]FF[4]SZ[19]
GN[Why the diagonal response]
PC[http://senseis.xmp.net/?InvasionOfThirdLineThreeSpaceExtension]AP[GoWiki:2009]
DT[2011-10-28]
C[Diagram from http://senseis.xmp.net/?InvasionOfThirdLineThreeSpaceExtension

Why the diagonal response]
PL[B]

AB[gq][kq]
AW[iq]

;B[hp]C[B1]MN[1]
;W[ip]C[W2]MN[2]
;B[io]C[B3]MN[3]
;W[kp]C[W4]MN[4]
;B[jp]C[B5]MN[5]
;W[jq]C[W6]MN[6]
;B[jo]C[B7]MN[7]
;W[lq]C[W8]MN[8]
;B[kr]C[B9]MN[9]
;W[lr]C[W10]MN[10]

;
)
