for p1, p2, p3, p4 being Point of (TOP-REAL 2)
for a, b, c, d being Real
for P, Q being Subset of (TOP-REAL 2) st a < b & c < d & p1 `2 = d & p2 `2 = d & p3 `2 = c & p4 `2 = c & a <= p1 `1 & p1 `1 < p2 `1 & p2 `1 <= b & a < p4 `1 & p4 `1 < p3 `1 & p3 `1 <= b & P is_an_arc_of p1,p3 & Q is_an_arc_of p2,p4 & P c= closed_inside_of_rectangle (a,b,c,d) & Q c= closed_inside_of_rectangle (a,b,c,d) holds
P meets Q