let p1, p2 be Point of (TOP-REAL 2); :: thesis: for P being non empty compact Subset of (TOP-REAL 2) st P = { p where p is Point of (TOP-REAL 2) : |.p.| = 1 } & ( p2 `2 >= 0 or p2 `1 >= 0 ) & LE p1,p2,P & not p1 `2 >= 0 holds
p1 `1 >= 0
let P be non empty compact Subset of (TOP-REAL 2); :: thesis: ( P = { p where p is Point of (TOP-REAL 2) : |.p.| = 1 } & ( p2 `2 >= 0 or p2 `1 >= 0 ) & LE p1,p2,P & not p1 `2 >= 0 implies p1 `1 >= 0 )
assume A1:
( P = { p where p is Point of (TOP-REAL 2) : |.p.| = 1 } & ( p2 `2 >= 0 or p2 `1 >= 0 ) & LE p1,p2,P )
; :: thesis: ( p1 `2 >= 0 or p1 `1 >= 0 )
then A2:
P is being_simple_closed_curve
by JGRAPH_3:36;
then A3:
Lower_Arc P is_an_arc_of E-max P, W-min P
by JORDAN6:def 9;
A4:
( P = { p where p is Point of (TOP-REAL 2) : |.p.| = 1 } & p1 in P & p2 in P & ( p2 `2 >= 0 or p2 `1 >= 0 ) & LE p1,p2,P )
by A1, A2, JORDAN7:5;
A5:
Upper_Arc P = { p where p is Point of (TOP-REAL 2) : ( p in P & p `2 >= 0 ) }
by A1, Th37;