let C be Simple_closed_curve; for p being Point of (TOP-REAL 2) holds L_Segment ((Lower_Arc C),(E-max C),(W-min C),p) = Segment ((Lower_Arc C),(E-max C),(W-min C),(E-max C),p)
let p be Point of (TOP-REAL 2); L_Segment ((Lower_Arc C),(E-max C),(W-min C),p) = Segment ((Lower_Arc C),(E-max C),(W-min C),(E-max C),p)
Lower_Arc C is_an_arc_of E-max C, W-min C
by JORDAN6:50;
then
R_Segment ((Lower_Arc C),(E-max C),(W-min C),(E-max C)) = Lower_Arc C
by JORDAN6:24;
hence Segment ((Lower_Arc C),(E-max C),(W-min C),(E-max C),p) =
(Lower_Arc C) /\ (L_Segment ((Lower_Arc C),(E-max C),(W-min C),p))
by JORDAN6:def 5
.=
L_Segment ((Lower_Arc C),(E-max C),(W-min C),p)
by JORDAN6:19, XBOOLE_1:28
;
verum