let p1, p2 be Point of (TOP-REAL 2); for b, c being real number st p1 `1 < b & c < p2 `2 & c <= p1 `2 & p1 `2 <= p2 `2 & p1 `1 <= p2 `1 & p2 `1 <= b holds
LE p1,p2, rectangle (p1 `1 ),b,c,(p2 `2 )
let b, c be real number ; ( p1 `1 < b & c < p2 `2 & c <= p1 `2 & p1 `2 <= p2 `2 & p1 `1 <= p2 `1 & p2 `1 <= b implies LE p1,p2, rectangle (p1 `1 ),b,c,(p2 `2 ) )
set a = p1 `1 ;
set d = p2 `2 ;
set K = rectangle (p1 `1 ),b,c,(p2 `2 );
assume that
A1:
p1 `1 < b
and
A2:
c < p2 `2
and
A3:
c <= p1 `2
and
A4:
p1 `2 <= p2 `2
and
A5:
p1 `1 <= p2 `1
and
A6:
p2 `1 <= b
; LE p1,p2, rectangle (p1 `1 ),b,c,(p2 `2 )
A7:
p1 in LSeg |[(p1 `1 ),c]|,|[(p1 `1 ),(p2 `2 )]|
by A2, A3, A4, JGRAPH_6:10;
p2 in LSeg |[(p1 `1 ),(p2 `2 )]|,|[b,(p2 `2 )]|
by A1, A5, A6, Th1;
hence
LE p1,p2, rectangle (p1 `1 ),b,c,(p2 `2 )
by A1, A2, A7, JGRAPH_6:69; verum