intros p q H' H'0 H'1.
apply Rlt_Fexp_eq_Zlt with (radix := radix); auto with zarith.
apply trans_equal with (- dExp b)%Z.
case H'; auto.
intros H1 H2; case H2; auto.
apply sym_equal; case H'0; auto.
intros H1 H2; case H2; auto.
Qed.

Theorem LtFsubnormal :
forall p q : float,
Fsubnormal p -> Fsubnormal q -> (Fnum p < Fnum q)%Z -> (p < q)%R.