(;GM[1]FF[4]SZ[19]
GN[B3 is a brilliant tesuji but W4 is a strong counter making the position a ko.]
PC[http://senseis.xmp.net/?XuanxuanQijingProblem171/Solution]AP[GoWiki:2009]
DT[2013-04-01]
C[Diagram from http://senseis.xmp.net/?XuanxuanQijingProblem171/Solution

B3 is a brilliant tesuji but W4 is a strong counter making the position a ko.]
PL[B]

AB[gn][hn][in][jn][fo][ko][fp][hp][kp][cq][eq][kq][mq][dr][ds]
AW[go][ho][gp][jp][gq][jq][hr]

;B[ip]C[B1]MN[1]
;W[io]C[W2]MN[2]
;B[ks]C[B3]MN[3]
;W[ir]C[W4]MN[4]
;B[fr]C[B5]MN[5]
;W[kr]C[W6]MN[6]
;B[lr]C[B7]MN[7]
;W[js]C[W8]MN[8]

;
)
