unfold FNodd, FNeven, FNPred in |- *.
intros p H' H'0.
rewrite FcanonicFnormalizeEq; auto with float arith.
apply FoddPred; auto.
Qed.

Theorem FNevenOrFNodd : forall p : float, FNeven p \/ FNodd p.
intros p; unfold FNeven, FNodd in |- *; apply FevenOrFodd.