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-(************************************************************************)
-(* v * The Coq Proof Assistant / The Coq Development Team *)
-(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
-(* \VV/ **************************************************************)
-(* // * This file is distributed under the terms of the *)
-(* * GNU Lesser General Public License Version 2.1 *)
-(************************************************************************)
-
-(* $Id: Field_Theory.v,v 1.2.2.1 2004/07/16 19:30:17 herbelin Exp $ *)
-
-Require Peano_dec.
-Require Ring.
-Require Field_Compl.
-
-Record Field_Theory : Type :=
-{ A : Type;
- Aplus : A -> A -> A;
- Amult : A -> A -> A;
- Aone : A;
- Azero : A;
- Aopp : A -> A;
- Aeq : A -> A -> bool;
- Ainv : A -> A;
- Aminus : (field_rel_option A);
- Adiv : (field_rel_option A);
- RT : (Ring_Theory Aplus Amult Aone Azero Aopp Aeq);
- Th_inv_def : (n:A)~(n=Azero)->(Amult (Ainv n) n)=Aone
-}.
-
-(* The reflexion structure *)
-Inductive ExprA : Set :=
-| EAzero : ExprA
-| EAone : ExprA
-| EAplus : ExprA -> ExprA -> ExprA
-| EAmult : ExprA -> ExprA -> ExprA
-| EAopp : ExprA -> ExprA
-| EAinv : ExprA -> ExprA
-| EAvar : nat -> ExprA.
-
-(**** Decidability of equality ****)
-
-Lemma eqExprA_O:(e1,e2:ExprA){e1=e2}+{~e1=e2}.
-Proof.
- Double Induction e1 e2;Try Intros;
- Try (Left;Reflexivity) Orelse Try (Right;Discriminate).
- Elim (H1 e0);Intro y;Elim (H2 e);Intro y0;
- Try (Left; Rewrite y; Rewrite y0;Auto)
- Orelse (Right;Red;Intro;Inversion H3;Auto).
- Elim (H1 e0);Intro y;Elim (H2 e);Intro y0;
- Try (Left; Rewrite y; Rewrite y0;Auto)
- Orelse (Right;Red;Intro;Inversion H3;Auto).
- Elim (H0 e);Intro y.
- Left; Rewrite y; Auto.
- Right;Red; Intro;Inversion H1;Auto.
- Elim (H0 e);Intro y.
- Left; Rewrite y; Auto.
- Right;Red; Intro;Inversion H1;Auto.
- Elim (eq_nat_dec n n0);Intro y.
- Left; Rewrite y; Auto.
- Right;Red;Intro;Inversion H;Auto.
-Defined.
-
-Definition eq_nat_dec := Eval Compute in Peano_dec.eq_nat_dec.
-Definition eqExprA := Eval Compute in eqExprA_O.
-
-(**** Generation of the multiplier ****)
-
-Fixpoint mult_of_list [e:(listT ExprA)]: ExprA :=
- Cases e of
- | nilT => EAone
- | (consT e1 l1) => (EAmult e1 (mult_of_list l1))
- end.
-
-Section Theory_of_fields.
-
-Variable T : Field_Theory.
-
-Local AT := (A T).
-Local AplusT := (Aplus T).
-Local AmultT := (Amult T).
-Local AoneT := (Aone T).
-Local AzeroT := (Azero T).
-Local AoppT := (Aopp T).
-Local AeqT := (Aeq T).
-Local AinvT := (Ainv T).
-Local RTT := (RT T).
-Local Th_inv_defT := (Th_inv_def T).
-
-Add Abstract Ring (A T) (Aplus T) (Amult T) (Aone T) (Azero T) (Aopp T)
- (Aeq T) (RT T).
-
-Add Abstract Ring AT AplusT AmultT AoneT AzeroT AoppT AeqT RTT.
-
-(***************************)
-(* Lemmas to be used *)
-(***************************)
-
-Lemma AplusT_sym:(r1,r2:AT)(AplusT r1 r2)=(AplusT r2 r1).
-Proof.
- Intros;Ring.
-Save.
-
-Lemma AplusT_assoc:(r1,r2,r3:AT)(AplusT (AplusT r1 r2) r3)=
- (AplusT r1 (AplusT r2 r3)).
-Proof.
- Intros;Ring.
-Save.
-
-Lemma AmultT_sym:(r1,r2:AT)(AmultT r1 r2)=(AmultT r2 r1).
-Proof.
- Intros;Ring.
-Save.
-
-Lemma AmultT_assoc:(r1,r2,r3:AT)(AmultT (AmultT r1 r2) r3)=
- (AmultT r1 (AmultT r2 r3)).
-Proof.
- Intros;Ring.
-Save.
-
-Lemma AplusT_Ol:(r:AT)(AplusT AzeroT r)=r.
-Proof.
- Intros;Ring.
-Save.
-
-Lemma AmultT_1l:(r:AT)(AmultT AoneT r)=r.
-Proof.
- Intros;Ring.
-Save.
-
-Lemma AplusT_AoppT_r:(r:AT)(AplusT r (AoppT r))=AzeroT.
-Proof.
- Intros;Ring.
-Save.
-
-Lemma AmultT_AplusT_distr:(r1,r2,r3:AT)(AmultT r1 (AplusT r2 r3))=
- (AplusT (AmultT r1 r2) (AmultT r1 r3)).
-Proof.
- Intros;Ring.
-Save.
-
-Lemma r_AplusT_plus:(r,r1,r2:AT)(AplusT r r1)=(AplusT r r2)->r1=r2.
-Proof.
- Intros; Transitivity (AplusT (AplusT (AoppT r) r) r1).
- Ring.
- Transitivity (AplusT (AplusT (AoppT r) r) r2).
- Repeat Rewrite -> AplusT_assoc; Rewrite <- H; Reflexivity.
- Ring.
-Save.
-
-Lemma r_AmultT_mult:
- (r,r1,r2:AT)(AmultT r r1)=(AmultT r r2)->~r=AzeroT->r1=r2.
-Proof.
- Intros; Transitivity (AmultT (AmultT (AinvT r) r) r1).
- Rewrite Th_inv_defT;[Symmetry; Apply AmultT_1l;Auto|Auto].
- Transitivity (AmultT (AmultT (AinvT r) r) r2).
- Repeat Rewrite AmultT_assoc; Rewrite H; Trivial.
- Rewrite Th_inv_defT;[Apply AmultT_1l;Auto|Auto].
-Save.
-
-Lemma AmultT_Or:(r:AT) (AmultT r AzeroT)=AzeroT.
-Proof.
- Intro; Ring.
-Save.
-
-Lemma AmultT_Ol:(r:AT)(AmultT AzeroT r)=AzeroT.
-Proof.
- Intro; Ring.
-Save.
-
-Lemma AmultT_1r:(r:AT)(AmultT r AoneT)=r.
-Proof.
- Intro; Ring.
-Save.
-
-Lemma AinvT_r:(r:AT)~r=AzeroT->(AmultT r (AinvT r))=AoneT.
-Proof.
- Intros; Rewrite -> AmultT_sym; Apply Th_inv_defT; Auto.
-Save.
-
-Lemma without_div_O_contr:
- (r1,r2:AT)~(AmultT r1 r2)=AzeroT ->~r1=AzeroT/\~r2=AzeroT.
-Proof.
- Intros r1 r2 H; Split; Red; Intro; Apply H; Rewrite H0; Ring.
-Save.
-
-(************************)
-(* Interpretation *)
-(************************)
-
-(**** ExprA --> A ****)
-
-Fixpoint interp_ExprA [lvar:(listT (prodT AT nat));e:ExprA] : AT :=
- Cases e of
- | EAzero => AzeroT
- | EAone => AoneT
- | (EAplus e1 e2) => (AplusT (interp_ExprA lvar e1) (interp_ExprA lvar e2))
- | (EAmult e1 e2) => (AmultT (interp_ExprA lvar e1) (interp_ExprA lvar e2))
- | (EAopp e) => ((Aopp T) (interp_ExprA lvar e))
- | (EAinv e) => ((Ainv T) (interp_ExprA lvar e))
- | (EAvar n) => (assoc_2nd AT nat eq_nat_dec lvar n AzeroT)
- end.
-
-(************************)
-(* Simplification *)
-(************************)
-
-(**** Associativity ****)
-
-Definition merge_mult :=
- Fix merge_mult {merge_mult [e1:ExprA] : ExprA -> ExprA :=
- [e2:ExprA]Cases e1 of
- | (EAmult t1 t2) =>
- Cases t2 of
- | (EAmult t2 t3) => (EAmult t1 (EAmult t2 (merge_mult t3 e2)))
- | _ => (EAmult t1 (EAmult t2 e2))
- end
- | _ => (EAmult e1 e2)
- end}.
-
-Fixpoint assoc_mult [e:ExprA] : ExprA :=
- Cases e of
- | (EAmult e1 e3) =>
- Cases e1 of
- | (EAmult e1 e2) =>
- (merge_mult (merge_mult (assoc_mult e1) (assoc_mult e2))
- (assoc_mult e3))
- | _ => (EAmult e1 (assoc_mult e3))
- end
- | _ => e
- end.
-
-Definition merge_plus :=
- Fix merge_plus {merge_plus [e1:ExprA]:ExprA->ExprA:=
- [e2:ExprA]Cases e1 of
- | (EAplus t1 t2) =>
- Cases t2 of
- | (EAplus t2 t3) => (EAplus t1 (EAplus t2 (merge_plus t3 e2)))
- | _ => (EAplus t1 (EAplus t2 e2))
- end
- | _ => (EAplus e1 e2)
- end}.
-
-Fixpoint assoc [e:ExprA] : ExprA :=
- Cases e of
- | (EAplus e1 e3) =>
- Cases e1 of
- | (EAplus e1 e2) =>
- (merge_plus (merge_plus (assoc e1) (assoc e2)) (assoc e3))
- | _ => (EAplus (assoc_mult e1) (assoc e3))
- end
- | _ => (assoc_mult e)
- end.
-
-Lemma merge_mult_correct1:
- (e1,e2,e3:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (merge_mult (EAmult e1 e2) e3))=
- (interp_ExprA lvar (EAmult e1 (merge_mult e2 e3))).
-Proof.
-Intros e1 e2;Generalize e1;Generalize e2;Clear e1 e2.
-Induction e2;Auto;Intros.
-Unfold 1 merge_mult;Fold merge_mult;
- Unfold 2 interp_ExprA;Fold interp_ExprA;
- Rewrite (H0 e e3 lvar);
- Unfold 1 interp_ExprA;Fold interp_ExprA;
- Unfold 5 interp_ExprA;Fold interp_ExprA;Auto.
-Save.
-
-Lemma merge_mult_correct:
- (e1,e2:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (merge_mult e1 e2))=
- (interp_ExprA lvar (EAmult e1 e2)).
-Proof.
-Induction e1;Auto;Intros.
-Elim e0;Try (Intros;Simpl;Ring).
-Unfold interp_ExprA in H2;Fold interp_ExprA in H2;
- Cut (AmultT (interp_ExprA lvar e2) (AmultT (interp_ExprA lvar e4)
- (AmultT (interp_ExprA lvar e) (interp_ExprA lvar e3))))=
- (AmultT (AmultT (AmultT (interp_ExprA lvar e) (interp_ExprA lvar e4))
- (interp_ExprA lvar e2)) (interp_ExprA lvar e3)).
-Intro H3;Rewrite H3;Rewrite <-H2;
- Rewrite merge_mult_correct1;Simpl;Ring.
-Ring.
-Save.
-
-Lemma assoc_mult_correct1:(e1,e2:ExprA)(lvar:(listT (prodT AT nat)))
- (AmultT (interp_ExprA lvar (assoc_mult e1))
- (interp_ExprA lvar (assoc_mult e2)))=
- (interp_ExprA lvar (assoc_mult (EAmult e1 e2))).
-Proof.
-Induction e1;Auto;Intros.
-Rewrite <-(H e0 lvar);Simpl;Rewrite merge_mult_correct;Simpl;
- Rewrite merge_mult_correct;Simpl;Auto.
-Save.
-
-Lemma assoc_mult_correct:
- (e:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (assoc_mult e))=(interp_ExprA lvar e).
-Proof.
-Induction e;Auto;Intros.
-Elim e0;Intros.
-Intros;Simpl;Ring.
-Simpl;Rewrite (AmultT_1l (interp_ExprA lvar (assoc_mult e1)));
- Rewrite (AmultT_1l (interp_ExprA lvar e1)); Apply H0.
-Simpl;Rewrite (H0 lvar);Auto.
-Simpl;Rewrite merge_mult_correct;Simpl;Rewrite merge_mult_correct;Simpl;
- Rewrite AmultT_assoc;Rewrite assoc_mult_correct1;Rewrite H2;Simpl;
- Rewrite <-assoc_mult_correct1 in H1;
- Unfold 3 interp_ExprA in H1;Fold interp_ExprA in H1;
- Rewrite (H0 lvar) in H1;
- Rewrite (AmultT_sym (interp_ExprA lvar e3) (interp_ExprA lvar e1));
- Rewrite <-AmultT_assoc;Rewrite H1;Rewrite AmultT_assoc;Ring.
-Simpl;Rewrite (H0 lvar);Auto.
-Simpl;Rewrite (H0 lvar);Auto.
-Simpl;Rewrite (H0 lvar);Auto.
-Save.
-
-Lemma merge_plus_correct1:
- (e1,e2,e3:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (merge_plus (EAplus e1 e2) e3))=
- (interp_ExprA lvar (EAplus e1 (merge_plus e2 e3))).
-Proof.
-Intros e1 e2;Generalize e1;Generalize e2;Clear e1 e2.
-Induction e2;Auto;Intros.
-Unfold 1 merge_plus;Fold merge_plus;
- Unfold 2 interp_ExprA;Fold interp_ExprA;
- Rewrite (H0 e e3 lvar);
- Unfold 1 interp_ExprA;Fold interp_ExprA;
- Unfold 5 interp_ExprA;Fold interp_ExprA;Auto.
-Save.
-
-Lemma merge_plus_correct:
- (e1,e2:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (merge_plus e1 e2))=
- (interp_ExprA lvar (EAplus e1 e2)).
-Proof.
-Induction e1;Auto;Intros.
-Elim e0;Try Intros;Try (Simpl;Ring).
-Unfold interp_ExprA in H2;Fold interp_ExprA in H2;
- Cut (AplusT (interp_ExprA lvar e2) (AplusT (interp_ExprA lvar e4)
- (AplusT (interp_ExprA lvar e) (interp_ExprA lvar e3))))=
- (AplusT (AplusT (AplusT (interp_ExprA lvar e) (interp_ExprA lvar e4))
- (interp_ExprA lvar e2)) (interp_ExprA lvar e3)).
-Intro H3;Rewrite H3;Rewrite <-H2;Rewrite merge_plus_correct1;Simpl;Ring.
-Ring.
-Save.
-
-Lemma assoc_plus_correct:(e1,e2:ExprA)(lvar:(listT (prodT AT nat)))
- (AplusT (interp_ExprA lvar (assoc e1)) (interp_ExprA lvar (assoc e2)))=
- (interp_ExprA lvar (assoc (EAplus e1 e2))).
-Proof.
-Induction e1;Auto;Intros.
-Rewrite <-(H e0 lvar);Simpl;Rewrite merge_plus_correct;Simpl;
- Rewrite merge_plus_correct;Simpl;Auto.
-Save.
-
-Lemma assoc_correct:
- (e:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (assoc e))=(interp_ExprA lvar e).
-Proof.
-Induction e;Auto;Intros.
-Elim e0;Intros.
-Simpl;Rewrite (H0 lvar);Auto.
-Simpl;Rewrite (H0 lvar);Auto.
-Simpl;Rewrite merge_plus_correct;Simpl;Rewrite merge_plus_correct;
- Simpl;Rewrite AplusT_assoc;Rewrite assoc_plus_correct;Rewrite H2;
- Simpl;Apply (r_AplusT_plus (interp_ExprA lvar (assoc e1))
- (AplusT (interp_ExprA lvar (assoc e2))
- (AplusT (interp_ExprA lvar e3) (interp_ExprA lvar e1)))
- (AplusT (AplusT (interp_ExprA lvar e2) (interp_ExprA lvar e3))
- (interp_ExprA lvar e1)));Rewrite <-AplusT_assoc;
- Rewrite (AplusT_sym (interp_ExprA lvar (assoc e1))
- (interp_ExprA lvar (assoc e2)));
- Rewrite assoc_plus_correct;Rewrite H1;Simpl;Rewrite (H0 lvar);
- Rewrite <-(AplusT_assoc (AplusT (interp_ExprA lvar e2)
- (interp_ExprA lvar e1))
- (interp_ExprA lvar e3) (interp_ExprA lvar e1));
- Rewrite (AplusT_assoc (interp_ExprA lvar e2) (interp_ExprA lvar e1)
- (interp_ExprA lvar e3));
- Rewrite (AplusT_sym (interp_ExprA lvar e1) (interp_ExprA lvar e3));
- Rewrite <-(AplusT_assoc (interp_ExprA lvar e2) (interp_ExprA lvar e3)
- (interp_ExprA lvar e1));Apply AplusT_sym.
-Unfold assoc;Fold assoc;Unfold interp_ExprA;Fold interp_ExprA;
- Rewrite assoc_mult_correct;Rewrite (H0 lvar);Simpl;Auto.
-Simpl;Rewrite (H0 lvar);Auto.
-Simpl;Rewrite (H0 lvar);Auto.
-Simpl;Rewrite (H0 lvar);Auto.
-Unfold assoc;Fold assoc;Unfold interp_ExprA;Fold interp_ExprA;
- Rewrite assoc_mult_correct;Simpl;Auto.
-Save.
-
-(**** Distribution *****)
-
-Fixpoint distrib_EAopp [e:ExprA] : ExprA :=
- Cases e of
- | (EAplus e1 e2) => (EAplus (distrib_EAopp e1) (distrib_EAopp e2))
- | (EAmult e1 e2) => (EAmult (distrib_EAopp e1) (distrib_EAopp e2))
- | (EAopp e) => (EAmult (EAopp EAone) (distrib_EAopp e))
- | e => e
- end.
-
-Definition distrib_mult_right :=
- Fix distrib_mult_right {distrib_mult_right [e1:ExprA]:ExprA->ExprA:=
- [e2:ExprA]Cases e1 of
- | (EAplus t1 t2) =>
- (EAplus (distrib_mult_right t1 e2) (distrib_mult_right t2 e2))
- | _ => (EAmult e1 e2)
- end}.
-
-Fixpoint distrib_mult_left [e1:ExprA] : ExprA->ExprA :=
- [e2:ExprA]
- Cases e1 of
- | (EAplus t1 t2) =>
- (EAplus (distrib_mult_left t1 e2) (distrib_mult_left t2 e2))
- | _ => (distrib_mult_right e2 e1)
- end.
-
-Fixpoint distrib_main [e:ExprA] : ExprA :=
- Cases e of
- | (EAmult e1 e2) => (distrib_mult_left (distrib_main e1) (distrib_main e2))
- | (EAplus e1 e2) => (EAplus (distrib_main e1) (distrib_main e2))
- | (EAopp e) => (EAopp (distrib_main e))
- | _ => e
- end.
-
-Definition distrib [e:ExprA] : ExprA := (distrib_main (distrib_EAopp e)).
-
-Lemma distrib_mult_right_correct:
- (e1,e2:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (distrib_mult_right e1 e2))=
- (AmultT (interp_ExprA lvar e1) (interp_ExprA lvar e2)).
-Proof.
-Induction e1;Try Intros;Simpl;Auto.
-Rewrite AmultT_sym;Rewrite AmultT_AplusT_distr;
- Rewrite (H e2 lvar);Rewrite (H0 e2 lvar);Ring.
-Save.
-
-Lemma distrib_mult_left_correct:
- (e1,e2:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (distrib_mult_left e1 e2))=
- (AmultT (interp_ExprA lvar e1) (interp_ExprA lvar e2)).
-Proof.
-Induction e1;Try Intros;Simpl.
-Rewrite AmultT_Ol;Rewrite distrib_mult_right_correct;Simpl;Apply AmultT_Or.
-Rewrite distrib_mult_right_correct;Simpl;
- Apply AmultT_sym.
-Rewrite AmultT_sym;
- Rewrite (AmultT_AplusT_distr (interp_ExprA lvar e2) (interp_ExprA lvar e)
- (interp_ExprA lvar e0));
- Rewrite (AmultT_sym (interp_ExprA lvar e2) (interp_ExprA lvar e));
- Rewrite (AmultT_sym (interp_ExprA lvar e2) (interp_ExprA lvar e0));
- Rewrite (H e2 lvar);Rewrite (H0 e2 lvar);Auto.
-Rewrite distrib_mult_right_correct;Simpl;Apply AmultT_sym.
-Rewrite distrib_mult_right_correct;Simpl;Apply AmultT_sym.
-Rewrite distrib_mult_right_correct;Simpl;Apply AmultT_sym.
-Rewrite distrib_mult_right_correct;Simpl;Apply AmultT_sym.
-Save.
-
-Lemma distrib_correct:
- (e:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (distrib e))=(interp_ExprA lvar e).
-Proof.
-Induction e;Intros;Auto.
-Simpl;Rewrite <- (H lvar);Rewrite <- (H0 lvar); Unfold distrib;Simpl;Auto.
-Simpl;Rewrite <- (H lvar);Rewrite <- (H0 lvar); Unfold distrib;Simpl;
- Apply distrib_mult_left_correct.
-Simpl;Fold AoppT;Rewrite <- (H lvar);Unfold distrib;Simpl;
- Rewrite distrib_mult_right_correct;
- Simpl;Fold AoppT;Ring.
-Save.
-
-(**** Multiplication by the inverse product ****)
-
-Lemma mult_eq:
- (e1,e2,a:ExprA)(lvar:(listT (prodT AT nat)))
- ~((interp_ExprA lvar a)=AzeroT)->
- (interp_ExprA lvar (EAmult a e1))=(interp_ExprA lvar (EAmult a e2))->
- (interp_ExprA lvar e1)=(interp_ExprA lvar e2).
-Proof.
- Simpl;Intros;
- Apply (r_AmultT_mult (interp_ExprA lvar a) (interp_ExprA lvar e1)
- (interp_ExprA lvar e2));Assumption.
-Save.
-
-Fixpoint multiply_aux [a,e:ExprA] : ExprA :=
- Cases e of
- | (EAplus e1 e2) =>
- (EAplus (EAmult a e1) (multiply_aux a e2))
- | _ => (EAmult a e)
- end.
-
-Definition multiply [e:ExprA] : ExprA :=
- Cases e of
- | (EAmult a e1) => (multiply_aux a e1)
- | _ => e
- end.
-
-Lemma multiply_aux_correct:
- (a,e:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (multiply_aux a e))=
- (AmultT (interp_ExprA lvar a) (interp_ExprA lvar e)).
-Proof.
-Induction e;Simpl;Intros;Try (Rewrite merge_mult_correct);Auto.
- Simpl;Rewrite (H0 lvar);Ring.
-Save.
-
-Lemma multiply_correct:
- (e:ExprA)(lvar:(listT (prodT AT nat)))
- (interp_ExprA lvar (multiply e))=(interp_ExprA lvar e).
-Proof.
- Induction e;Simpl;Auto.
- Intros;Apply multiply_aux_correct.
-Save.
-
-(**** Permutations and simplification ****)
-
-Fixpoint monom_remove [a,m:ExprA] : ExprA :=
- Cases m of
- | (EAmult m0 m1) =>
- (Cases (eqExprA m0 (EAinv a)) of
- | (left _) => m1
- | (right _) => (EAmult m0 (monom_remove a m1))
- end)
- | _ =>
- (Cases (eqExprA m (EAinv a)) of
- | (left _) => EAone
- | (right _) => (EAmult a m)
- end)
- end.
-
-Definition monom_simplif_rem :=
- Fix monom_simplif_rem {monom_simplif_rem/1:ExprA->ExprA->ExprA:=
- [a,m:ExprA]
- Cases a of
- | (EAmult a0 a1) => (monom_simplif_rem a1 (monom_remove a0 m))
- | _ => (monom_remove a m)
- end}.
-
-Definition monom_simplif [a,m:ExprA] : ExprA :=
- Cases m of
- | (EAmult a' m') =>
- (Cases (eqExprA a a') of
- | (left _) => (monom_simplif_rem a m')
- | (right _) => m
- end)
- | _ => m
- end.
-
-Fixpoint inverse_simplif [a,e:ExprA] : ExprA :=
- Cases e of
- | (EAplus e1 e2) => (EAplus (monom_simplif a e1) (inverse_simplif a e2))
- | _ => (monom_simplif a e)
- end.
-
-Lemma monom_remove_correct:(e,a:ExprA)
- (lvar:(listT (prodT AT nat)))~((interp_ExprA lvar a)=AzeroT)->
- (interp_ExprA lvar (monom_remove a e))=
- (AmultT (interp_ExprA lvar a) (interp_ExprA lvar e)).
-Proof.
-Induction e; Intros.
-Simpl;Case (eqExprA EAzero (EAinv a));Intros;[Inversion e0|Simpl;Trivial].
-Simpl;Case (eqExprA EAone (EAinv a));Intros;[Inversion e0|Simpl;Trivial].
-Simpl;Case (eqExprA (EAplus e0 e1) (EAinv a));Intros;[Inversion e2|
- Simpl;Trivial].
-Simpl;Case (eqExprA e0 (EAinv a));Intros.
-Rewrite e2;Simpl;Fold AinvT.
-Rewrite <-(AmultT_assoc (interp_ExprA lvar a) (AinvT (interp_ExprA lvar a))
- (interp_ExprA lvar e1));
- Rewrite AinvT_r;[Ring|Assumption].
-Simpl;Rewrite H0;Auto; Ring.
-Simpl;Fold AoppT;Case (eqExprA (EAopp e0) (EAinv a));Intros;[Inversion e1|
- Simpl;Trivial].
-Unfold monom_remove;Case (eqExprA (EAinv e0) (EAinv a));Intros.
-Case (eqExprA e0 a);Intros.
-Rewrite e2;Simpl;Fold AinvT;Rewrite AinvT_r;Auto.
-Inversion e1;Simpl;ElimType False;Auto.
-Simpl;Trivial.
-Unfold monom_remove;Case (eqExprA (EAvar n) (EAinv a));Intros;
- [Inversion e0|Simpl;Trivial].
-Save.
-
-Lemma monom_simplif_rem_correct:(a,e:ExprA)
- (lvar:(listT (prodT AT nat)))~((interp_ExprA lvar a)=AzeroT)->
- (interp_ExprA lvar (monom_simplif_rem a e))=
- (AmultT (interp_ExprA lvar a) (interp_ExprA lvar e)).
-Proof.
-Induction a;Simpl;Intros; Try Rewrite monom_remove_correct;Auto.
-Elim (without_div_O_contr (interp_ExprA lvar e)
- (interp_ExprA lvar e0) H1);Intros.
-Rewrite (H0 (monom_remove e e1) lvar H3);Rewrite monom_remove_correct;Auto.
-Ring.
-Save.
-
-Lemma monom_simplif_correct:(e,a:ExprA)
- (lvar:(listT (prodT AT nat)))~((interp_ExprA lvar a)=AzeroT)->
- (interp_ExprA lvar (monom_simplif a e))=(interp_ExprA lvar e).
-Proof.
-Induction e;Intros;Auto.
-Simpl;Case (eqExprA a e0);Intros.
-Rewrite <-e2;Apply monom_simplif_rem_correct;Auto.
-Simpl;Trivial.
-Save.
-
-Lemma inverse_correct:
- (e,a:ExprA)(lvar:(listT (prodT AT nat)))~((interp_ExprA lvar a)=AzeroT)->
- (interp_ExprA lvar (inverse_simplif a e))=(interp_ExprA lvar e).
-Proof.
-Induction e;Intros;Auto.
-Simpl;Rewrite (H0 a lvar H1); Rewrite monom_simplif_correct ; Auto.
-Unfold inverse_simplif;Rewrite monom_simplif_correct ; Auto.
-Save.
-
-End Theory_of_fields.