fact: Definition subset xi yi := match xi, yi with | Ibnd xl xu, Ibnd yl yu => match xl, xu with | Xreal xl, Xreal xu => (xu < xl)%R | _, _ => False end \/ (le_lower yl xl /\ le_upper xu yu) | _, Inan => True | _, _ => False end.
imports: Coq(Bool Reals Psatz) Coquelicot(Coquelicot) Stdlib Xreal Basic