let n be Element of NAT ; :: thesis: for C being Simple_closed_curve
for j, k being Element of NAT st 1 <= j & j <= k & k <= width (Gauge C,(n + 1)) & (Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k in Upper_Arc (L~ (Cage C,(n + 1))) & (Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j in Lower_Arc (L~ (Cage C,(n + 1))) holds
LSeg ((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j),((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k) meets Upper_Arc C
let C be Simple_closed_curve; :: thesis: for j, k being Element of NAT st 1 <= j & j <= k & k <= width (Gauge C,(n + 1)) & (Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k in Upper_Arc (L~ (Cage C,(n + 1))) & (Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j in Lower_Arc (L~ (Cage C,(n + 1))) holds
LSeg ((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j),((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k) meets Upper_Arc C
let j, k be Element of NAT ; :: thesis: ( 1 <= j & j <= k & k <= width (Gauge C,(n + 1)) & (Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k in Upper_Arc (L~ (Cage C,(n + 1))) & (Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j in Lower_Arc (L~ (Cage C,(n + 1))) implies LSeg ((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j),((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k) meets Upper_Arc C )
assume that
A1:
( 1 <= j & j <= k & k <= width (Gauge C,(n + 1)) )
and
A2:
(Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k in Upper_Arc (L~ (Cage C,(n + 1)))
and
A3:
(Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j in Lower_Arc (L~ (Cage C,(n + 1)))
; :: thesis: LSeg ((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j),((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k) meets Upper_Arc C
A4:
len (Gauge C,(n + 1)) >= 4
by JORDAN8:13;
then A5:
len (Gauge C,(n + 1)) >= 3
by XXREAL_0:2;
len (Gauge C,(n + 1)) >= 2
by A4, XXREAL_0:2;
then
1 < Center (Gauge C,(n + 1))
by JORDAN1B:15;
hence
LSeg ((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),j),((Gauge C,(n + 1)) * (Center (Gauge C,(n + 1))),k) meets Upper_Arc C
by A1, A2, A3, A5, Th26, JORDAN1B:16; :: thesis: verum