(;GM[1]FF[4]SZ[19]
GN[The key difference]
PC[http://senseis.xmp.net/?BiggestCorner]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BiggestCorner

The key difference]
PL[W]

AB[ia][db][fb][ib][ec][ic][id][be][ie][bf][if][ig][ih][ai][bi][ci][di][ei][fi][gi][hi][ii]
AW[cb][cc][fc][ed][ce]
LB[hb:a]

;W[gb]C[W1]MN[1]
;B[gc]C[B2]MN[2]
;W[fd]C[W3]MN[3]
;B[bd]C[B4]MN[4]

;LB[hb:a]
)
