intros P H' p q H'0.
case (Req_dec p q); intros Eq1.
rewrite <- Eq1.
replace (p - p)%R with 0%R; [ idtac | ring ].
rewrite Rabs_R0; auto.
unfold Fulp, FtoRradix, FtoR in |- *; simpl in |- *; auto with real arith.
case H'.
intros H'1 H'2; elim H'2; intros H'3 H'4; elim H'4; intros H'5 H'6;
case H'5 with (1 := H'0); clear H'5 H'4 H'2; intros H'5.
rewrite Rabs_right; auto.
cut (Fbounded b q); [ intros B0 | case H'5; auto ].
apply Rlt_le_trans with (2 := FulpSuc q B0).
apply Rplus_lt_reg_l with (r := FtoR radix q).
repeat rewrite Rplus_minus; auto.
case (Rle_or_lt (FNSucc b radix precision q) p); auto.
intros H'2; absurd (FNSucc b radix precision q <= q)%R; auto.
apply Rgt_not_le; red in |- *; unfold FtoRradix in |- *;
auto with real float arith.
case H'5; auto.
intros H'4 H'7; elim H'7; intros H'8 H'9; apply H'9; clear H'7; auto.
apply (FcanonicBound radix b); auto with float arith.
apply Rle_ge; apply Rplus_le_reg_l with (r := FtoR radix q).
repeat rewrite Rplus_minus; auto.
rewrite Rplus_0_r; apply isMin_inv1 with (1 := H'5); auto.
rewrite Faux.Rabsolu_left1; auto.
rewrite Ropp_minus_distr; auto.
cut (Fbounded b q); [ intros B0 | case H'5; auto ].
apply Rlt_le_trans with (2 := FulpPred q B0).
apply Ropp_lt_cancel; repeat rewrite Rminus_0_l.
apply Rplus_lt_reg_l with (r := FtoR radix q).
repeat rewrite Rplus_minus; auto.
case (Rle_or_lt p (FNPred b radix precision q)); auto.
intros H'2; absurd (q <= FNPred b radix precision q)%R; auto.
apply Rgt_not_le; red in |- *; unfold FtoRradix in |- *;
auto with real float arith.
case H'5; auto.
intros H'4 H'7; elim H'7; intros H'8 H'9; apply H'9; clear H'7; auto.
apply (FcanonicBound radix b); auto with float arith.
intros H1; apply Rplus_lt_compat_l; auto with real; apply Ropp_lt_contravar;
unfold Rminus in |- *; auto with real.
apply Rplus_le_reg_l with (r := FtoR radix q).
repeat rewrite Rplus_minus; auto.
rewrite Rplus_0_r; apply isMax_inv1 with (1 := H'5).
Qed.

Theorem RoundedModeErrorExpStrict :
forall P,
RoundedModeP b radix P ->
forall (p q : float) (x : R),
Fbounded b p ->
Fbounded b q ->
P x p -> q = (x - p)%R :>R -> q <> 0%R :>R -> (Fexp q < Fexp p)%Z.