let p1, p2 be Point of (TOP-REAL 2); for c, d being real number st p1 `1 < p2 `1 & c < d & c <= p1 `2 & p1 `2 <= d & c <= p2 `2 & p2 `2 <= d holds
LE p1,p2, rectangle (p1 `1 ),(p2 `1 ),c,d
let c, d be real number ; ( p1 `1 < p2 `1 & c < d & c <= p1 `2 & p1 `2 <= d & c <= p2 `2 & p2 `2 <= d implies LE p1,p2, rectangle (p1 `1 ),(p2 `1 ),c,d )
set a = p1 `1 ;
set b = p2 `1 ;
set K = rectangle (p1 `1 ),(p2 `1 ),c,d;
assume that
A1:
p1 `1 < p2 `1
and
A2:
c < d
and
A3:
c <= p1 `2
and
A4:
p1 `2 <= d
and
A5:
c <= p2 `2
and
A6:
p2 `2 <= d
; LE p1,p2, rectangle (p1 `1 ),(p2 `1 ),c,d
A7:
p2 in LSeg |[(p2 `1 ),c]|,|[(p2 `1 ),d]|
by A2, A5, A6, JGRAPH_6:10;
p1 in LSeg |[(p1 `1 ),c]|,|[(p1 `1 ),d]|
by A2, A3, A4, JGRAPH_6:10;
hence
LE p1,p2, rectangle (p1 `1 ),(p2 `1 ),c,d
by A1, A2, A7, JGRAPH_6:69; verum