let n be Element of NAT ; TOP-REAL n is pathwise_connected
set T = TOP-REAL n;
let a, b be Point of (TOP-REAL n); BORSUK_2:def 3 a,b are_connected
set L = LSeg a,b;
per cases
( a <> b or a = b )
;
suppose
a <> b
;
a,b are_connected then consider f being
Function of
I[01] ,
((TOP-REAL n) | (LSeg a,b)) such that
for
x being
Real st
x in [.0 ,1.] holds
f . x = ((1 - x) * a) + (x * b)
and A1:
f is
being_homeomorphism
and A2:
(
f . 0 = a &
f . 1
= b )
by Th4;
rng f c= [#] ((TOP-REAL n) | (LSeg a,b))
;
then
rng f c= LSeg a,
b
by PRE_TOPC:def 10;
then
(
dom f = the
carrier of
I[01] &
rng f c= the
carrier of
(TOP-REAL n) )
by FUNCT_2:def 1, XBOOLE_1:1;
then reconsider g =
f as
Function of
I[01] ,
(TOP-REAL n) by FUNCT_2:def 1, RELSET_1:11;
f is
continuous
by A1, TOPS_2:def 5;
then
g is
continuous
by PRE_TOPC:56;
hence
a,
b are_connected
by A2, BORSUK_2:def 1;
verum end; end;