intros x y H' H'0.
apply le_IZR.
apply (Rle_monotony_contra_exp radix) with (z := Fexp x);
auto with real arith.
pattern (Fexp x) at 2 in |- *; rewrite H'0; auto.
Qed.

Theorem LtR0Fnum : forall p : float, (0 < p)%R -> (0 < Fnum p)%Z.
intros p H'.