use int.Int
use real.FromInt
use real.RealInfix
use real.Abs

goal g1 : from_int 100 = 100.
goal g2: forall x. -5 <= x <= 5 -> abs (from_int x) <=. 5.
goal g3: forall x. x <= 5 -> 10. *. from_int x <=. 50.
