let n be Element of NAT ; :: thesis: for p1, p2 being Point of (TOP-REAL n) holds LSeg p1,p2 is compact
let p1, p2 be Point of (TOP-REAL n); :: thesis: LSeg p1,p2 is compact
set P = LSeg p1,p2;
set T = (TOP-REAL n) | (LSeg p1,p2);
now per cases
( p1 = p2 or p1 <> p2 )
;
suppose
p1 <> p2
;
:: thesis: (TOP-REAL n) | (LSeg p1,p2) is compact then
LSeg p1,
p2 is_an_arc_of p1,
p2
by TOPREAL1:15;
then consider f being
Function of
I[01] ,
((TOP-REAL n) | (LSeg p1,p2)) such that A2:
f is
being_homeomorphism
and
(
f . 0 = p1 &
f . 1
= p2 )
by TOPREAL1:def 2;
A3:
f is
continuous
by A2, TOPS_2:def 5;
A4:
I[01] is
compact
by HEINE:11, TOPMETR:27;
rng f = [#] ((TOP-REAL n) | (LSeg p1,p2))
by A2, TOPS_2:def 5;
hence
(TOP-REAL n) | (LSeg p1,p2) is
compact
by A3, A4, COMPTS_1:23;
:: thesis: verum end; end; end;
hence
LSeg p1,p2 is compact
by COMPTS_1:12; :: thesis: verum