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(*         *      The Rocq Prover / The Rocq Development Team           *)
(*  v      *         Copyright INRIA, CNRS and contributors             *)
(* <O___,, * (see version control and CREDITS file for authors & dates) *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
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(*                      Evgeny Makarov, INRIA, 2007                     *)
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Require Stdlib.micromega.Tauto.
Set Implicit Arguments.
Section Micromega.
(* Assume we have a strict(ly?) ordered ring *)
Variable R : Type.
Variables rO rI : R.
Variables rplus rtimes rminus: R -> R -> R.
Variable ropp : R -> R.
Variables req rle rlt : R -> R -> Prop.
Variable sor : SOR rO rI rplus rtimes rminus ropp req rle rlt.
Notation "0" := rO.
Notation "1" := rI.
Notation "x + y" := (rplus x y).
Notation "x * y " := (rtimes x y).
Notation "x - y " := (rminus x y).
Notation "- x" := (ropp x).
Notation "x == y" := (req x y).
Notation "x ~= y" := (~ req x y).
Notation "x <= y" := (rle x y).
Notation "x < y" := (rlt x y).
(* Assume we have a type of coefficients C and a morphism from C to R *)
Variable C : Type.
Variables cO cI : C.
Variables cplus ctimes cminus: C -> C -> C.
Variable copp : C -> C.
Variables ceqb cleb : C -> C -> bool.
Variable phi : C -> R.
(* Power coefficients *)
Variable E : Type. (* the type of exponents *)
Variable pow_phi : N -> E.
Variable rpow : R -> E -> R.
Notation "[ x ]" := (phi x).
Notation "x [=] y" := (ceqb x y).
Notation "x [<=] y" := (cleb x y).
(* Let's collect all hypotheses in addition to the ordered ring axioms into one structure *)
Record SORaddon := mk_SOR_addon {
SORrm : ring_morph 0 1 rplus rtimes rminus ropp req cO cI cplus ctimes cminus copp ceqb phi;
SORpower : power_theory rI rtimes req pow_phi rpow;
SORcneqb_morph : forall x y : C, x [=] y = false -> [x] ~= [y];
SORcleb_morph : forall x y : C, x [<=] y = true -> [x] <= [y]
}.
Variable addon : SORaddon.
Add Relation R req
reflexivity proved by (@Equivalence_Reflexive _ _ (SORsetoid sor))
symmetry proved by (@Equivalence_Symmetric _ _ (SORsetoid sor))
transitivity proved by (@Equivalence_Transitive _ _ (SORsetoid sor))
as micomega_sor_setoid.
Add Morphism rplus with signature req ==> req ==> req as rplus_morph.
Add Morphism rtimes with signature req ==> req ==> req as rtimes_morph.
Add Morphism ropp with signature req ==> req as ropp_morph.
Add Morphism rle with signature req ==> req ==> iff as rle_morph.
Add Morphism rlt with signature req ==> req ==> iff as rlt_morph.
Add Morphism rminus with signature req ==> req ==> req as rminus_morph.
Definition cneqb (x y : C) := negb (ceqb x y).
Definition cltb (x y : C) := (cleb x y) && (cneqb x y).
Notation "x [~=] y" := (cneqb x y).
Notation "x [<] y" := (cltb x y).
Ltac le_less := rewrite (Rle_lt_eq sor); left; try assumption.
Ltac le_equal := rewrite (Rle_lt_eq sor); right; try reflexivity; try assumption.
Ltac le_elim H := rewrite (Rle_lt_eq sor) in H; destruct H as [H | H].

Lemma cltb_sound : forall x y : C, x [<] y = true -> [x] < [y].
Definition PolC := Pol C. (* polynomials in generalized Horner form, defined in Ring_polynom or EnvRing *)
Definition PolEnv := Env R. (* For interpreting PolC *)
Definition eval_pol : PolEnv -> PolC -> R :=
Pphi rplus rtimes phi.