(;GM[1]FF[4]SZ[23:9]
GN[Killing [eternal life\]: Since W3 is an incursion, Black cannot reply with another incursion at the vital point ''a'', but must make a ko threat first. However, this is a fight Black cannot win. Once Black runs out of ko threats, the black group will die.]
PC[https://senseis.xmp.net/?IncursionGo]AP[GoWiki:2009]
DT[2023-04-18]
C[Diagram from https://senseis.xmp.net/?IncursionGo

Killing [eternal life\]: Since W3 is an incursion, Black cannot reply with another incursion at the vital point ''a'', but must make a ko threat first. However, this is a fight Black cannot win. Once Black runs out of ko threats, the black group will die.]
PL[W]

AB[da][ja][pa][va][ab][bb][db][gb][hb][jb][mb][nb][pb][sb][tb][vb][bc][dc][hc][jc][nc][pc][tc][vc][bd][dd][hd][jd][nd][pd][td][vd][de][je][pe][ve][af][cf][gf][if][mf][of][uf][bg][dg][hg][jg][ng][pg][tg][vg][bh][hh][nh][th]
AW[ba][ca][ha][ia][na][oa][ta][ua][cb][ib][ob][ub][cc][ic][oc][uc][ad][cd][gd][id][od][ud][be][ce][he][ie][ne][oe][te][ue][bf][hf][nf][tf][ag][gg][mg][sg]
LB[sf:a]

;W[gc]C[W1]MN[1]
;B[me]C[B2]MN[2]
;W[sd]C[W3]MN[3]

;LB[sf:a]
)
