let C be non empty connected compact Subset of ; ex p1, p2 being Point of st
( p1 <= p2 & C = [.p1,p2.] )
reconsider C' = C as closed-interval Subset of by Th55;
A1:
C' = [.(inf C'),(sup C').]
by INTEGRA1:5;
A2:
inf C' <= sup C'
by Th53;
then A3:
sup C' in C
by A1, XXREAL_1:1;
inf C' in C
by A1, A2, XXREAL_1:1;
then reconsider p1 = inf C', p2 = sup C' as Point of by A3;
take
p1
; ex p2 being Point of st
( p1 <= p2 & C = [.p1,p2.] )
take
p2
; ( p1 <= p2 & C = [.p1,p2.] )
thus
p1 <= p2
by Th53; C = [.p1,p2.]
thus
C = [.p1,p2.]
by INTEGRA1:5; verum