let f be FinSequence of (TOP-REAL 2); for p being Point of (TOP-REAL 2) st p in LSeg (f,1) holds
Index (p,f) = 1
let p be Point of (TOP-REAL 2); ( p in LSeg (f,1) implies Index (p,f) = 1 )
assume A1:
p in LSeg (f,1)
; Index (p,f) = 1
then A2:
Index (p,f) <= 1
by Th7;
LSeg (f,1) c= L~ f
by TOPREAL3:19;
then
Index (p,f) >= 1
by A1, Th8;
hence
Index (p,f) = 1
by A2, XXREAL_0:1; verum