let C be Simple_closed_curve; :: thesis: for n being Element of NAT st n is_sufficiently_large_for C holds
L~ (Span C,n) c= BDD C
let n be Element of NAT ; :: thesis: ( n is_sufficiently_large_for C implies L~ (Span C,n) c= BDD C )
assume A1:
n is_sufficiently_large_for C
; :: thesis: L~ (Span C,n) c= BDD C
then
C misses L~ (Span C,n)
by Th9;
then
L~ (Span C,n) c= C `
by SUBSET_1:43;
then A2:
L~ (Span C,n) c= (BDD C) \/ (UBD C)
by JORDAN2C:31;
UBD C misses L~ (Span C,n)
by A1, Th21;
hence
L~ (Span C,n) c= BDD C
by A2, XBOOLE_1:73; :: thesis: verum