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Diffstat (limited to 'plugins/setoid_ring/Ncring.v')
| -rw-r--r-- | plugins/setoid_ring/Ncring.v | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/plugins/setoid_ring/Ncring.v b/plugins/setoid_ring/Ncring.v new file mode 100644 index 00000000..9a30fa47 --- /dev/null +++ b/plugins/setoid_ring/Ncring.v @@ -0,0 +1,305 @@ +(************************************************************************) +(* v * The Coq Proof Assistant / The Coq Development Team *) +(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2010 *) +(* \VV/ **************************************************************) +(* // * This file is distributed under the terms of the *) +(* * GNU Lesser General Public License Version 2.1 *) +(************************************************************************) + +(* non commutative rings *) + +Require Import Setoid. +Require Import BinPos. +Require Import BinNat. +Require Export Morphisms Setoid Bool. +Require Export ZArith_base. +Require Export Algebra_syntax. + +Set Implicit Arguments. + +Class Ring_ops(T:Type) + {ring0:T} + {ring1:T} + {add:T->T->T} + {mul:T->T->T} + {sub:T->T->T} + {opp:T->T} + {ring_eq:T->T->Prop}. + +Instance zero_notation(T:Type)`{Ring_ops T}:Zero T:= ring0. +Instance one_notation(T:Type)`{Ring_ops T}:One T:= ring1. +Instance add_notation(T:Type)`{Ring_ops T}:Addition T:= add. +Instance mul_notation(T:Type)`{Ring_ops T}:@Multiplication T T:= mul. +Instance sub_notation(T:Type)`{Ring_ops T}:Subtraction T:= sub. +Instance opp_notation(T:Type)`{Ring_ops T}:Opposite T:= opp. +Instance eq_notation(T:Type)`{Ring_ops T}:@Equality T:= ring_eq. + +Class Ring `{Ro:Ring_ops}:={ + ring_setoid: Equivalence _==_; + ring_plus_comp: Proper (_==_ ==> _==_ ==>_==_) _+_; + ring_mult_comp: Proper (_==_ ==> _==_ ==>_==_) _*_; + ring_sub_comp: Proper (_==_ ==> _==_ ==>_==_) _-_; + ring_opp_comp: Proper (_==_==>_==_) -_; + ring_add_0_l : forall x, 0 + x == x; + ring_add_comm : forall x y, x + y == y + x; + ring_add_assoc : forall x y z, x + (y + z) == (x + y) + z; + ring_mul_1_l : forall x, 1 * x == x; + ring_mul_1_r : forall x, x * 1 == x; + ring_mul_assoc : forall x y z, x * (y * z) == (x * y) * z; + ring_distr_l : forall x y z, (x + y) * z == x * z + y * z; + ring_distr_r : forall x y z, z * ( x + y) == z * x + z * y; + ring_sub_def : forall x y, x - y == x + -y; + ring_opp_def : forall x, x + -x == 0 +}. +(* inutile! je sais plus pourquoi j'ai mis ca... +Instance ring_Ring_ops(R:Type)`{Ring R} + :@Ring_ops R 0 1 addition multiplication subtraction opposite equality. +*) +Existing Instance ring_setoid. +Existing Instance ring_plus_comp. +Existing Instance ring_mult_comp. +Existing Instance ring_sub_comp. +Existing Instance ring_opp_comp. + +Section Ring_power. + +Context {R:Type}`{Ring R}. + + Fixpoint pow_pos (x:R) (i:positive) {struct i}: R := + match i with + | xH => x + | xO i => let p := pow_pos x i in p * p + | xI i => let p := pow_pos x i in x * (p * p) + end. + + Definition pow_N (x:R) (p:N) := + match p with + | N0 => 1 + | Npos p => pow_pos x p + end. + +End Ring_power. + +Definition ZN(x:Z):= + match x with + Z0 => N0 + |Zpos p | Zneg p => Npos p +end. + +Instance power_ring {R:Type}`{Ring R} : Power:= + {power x y := pow_N x (ZN y)}. + +(** Interpretation morphisms definition*) + +Class Ring_morphism (C R:Type)`{Cr:Ring C} `{Rr:Ring R}`{Rh:Bracket C R}:= { + ring_morphism0 : [0] == 0; + ring_morphism1 : [1] == 1; + ring_morphism_add : forall x y, [x + y] == [x] + [y]; + ring_morphism_sub : forall x y, [x - y] == [x] - [y]; + ring_morphism_mul : forall x y, [x * y] == [x] * [y]; + ring_morphism_opp : forall x, [-x] == -[x]; + ring_morphism_eq : forall x y, x == y -> [x] == [y]}. + +Section Ring. + +Context {R:Type}`{Rr:Ring R}. + +(* Powers *) + + Lemma pow_pos_comm : forall x j, x * pow_pos x j == pow_pos x j * x. +induction j; simpl. rewrite <- ring_mul_assoc. +rewrite <- ring_mul_assoc. +rewrite <- IHj. rewrite (ring_mul_assoc (pow_pos x j) x (pow_pos x j)). +rewrite <- IHj. rewrite <- ring_mul_assoc. reflexivity. +rewrite <- ring_mul_assoc. rewrite <- IHj. +rewrite ring_mul_assoc. rewrite IHj. +rewrite <- ring_mul_assoc. rewrite IHj. reflexivity. reflexivity. +Qed. + + Lemma pow_pos_Psucc : forall x j, pow_pos x (Psucc j) == x * pow_pos x j. + Proof. + induction j; simpl. + rewrite IHj. +rewrite <- (ring_mul_assoc x (pow_pos x j) (x * pow_pos x j)). +rewrite (ring_mul_assoc (pow_pos x j) x (pow_pos x j)). + rewrite <- pow_pos_comm. +rewrite <- ring_mul_assoc. reflexivity. +reflexivity. reflexivity. +Qed. + + Lemma pow_pos_Pplus : forall x i j, + pow_pos x (i + j) == pow_pos x i * pow_pos x j. + Proof. + intro x;induction i;intros. + rewrite xI_succ_xO;rewrite Pplus_one_succ_r. + rewrite <- Pplus_diag;repeat rewrite <- Pplus_assoc. + repeat rewrite IHi. + rewrite Pplus_comm;rewrite <- Pplus_one_succ_r; + rewrite pow_pos_Psucc. + simpl;repeat rewrite ring_mul_assoc. reflexivity. + rewrite <- Pplus_diag;repeat rewrite <- Pplus_assoc. + repeat rewrite IHi. rewrite ring_mul_assoc. reflexivity. + rewrite Pplus_comm;rewrite <- Pplus_one_succ_r;rewrite pow_pos_Psucc. + simpl. reflexivity. + Qed. + + Definition id_phi_N (x:N) : N := x. + + Lemma pow_N_pow_N : forall x n, pow_N x (id_phi_N n) == pow_N x n. + Proof. + intros; reflexivity. + Qed. + + (** Identity is a morphism *) + (* + Instance IDmorph : Ring_morphism _ _ _ (fun x => x). + Proof. + apply (Build_Ring_morphism H6 H6 (fun x => x));intros; + try reflexivity. trivial. + Qed. +*) + (** rings are almost rings*) + Lemma ring_mul_0_l : forall x, 0 * x == 0. + Proof. + intro x. setoid_replace (0*x) with ((0+1)*x + -x). + rewrite ring_add_0_l. rewrite ring_mul_1_l . + rewrite ring_opp_def . fold zero. reflexivity. + rewrite ring_distr_l . rewrite ring_mul_1_l . + rewrite <- ring_add_assoc ; rewrite ring_opp_def . + rewrite ring_add_comm ; rewrite ring_add_0_l ;reflexivity. + Qed. + + Lemma ring_mul_0_r : forall x, x * 0 == 0. + Proof. + intro x; setoid_replace (x*0) with (x*(0+1) + -x). + rewrite ring_add_0_l ; rewrite ring_mul_1_r . + rewrite ring_opp_def ; fold zero; reflexivity. + + rewrite ring_distr_r ;rewrite ring_mul_1_r . + rewrite <- ring_add_assoc ; rewrite ring_opp_def . + rewrite ring_add_comm ; rewrite ring_add_0_l ;reflexivity. + Qed. + + Lemma ring_opp_mul_l : forall x y, -(x * y) == -x * y. + Proof. + intros x y;rewrite <- (ring_add_0_l (- x * y)). + rewrite ring_add_comm . + rewrite <- (ring_opp_def (x*y)). + rewrite ring_add_assoc . + rewrite <- ring_distr_l. + rewrite (ring_add_comm (-x));rewrite ring_opp_def . + rewrite ring_mul_0_l;rewrite ring_add_0_l ;reflexivity. + Qed. + +Lemma ring_opp_mul_r : forall x y, -(x * y) == x * -y. + Proof. + intros x y;rewrite <- (ring_add_0_l (x * - y)). + rewrite ring_add_comm . + rewrite <- (ring_opp_def (x*y)). + rewrite ring_add_assoc . + rewrite <- ring_distr_r . + rewrite (ring_add_comm (-y));rewrite ring_opp_def . + rewrite ring_mul_0_r;rewrite ring_add_0_l ;reflexivity. + Qed. + + Lemma ring_opp_add : forall x y, -(x + y) == -x + -y. + Proof. + intros x y;rewrite <- (ring_add_0_l (-(x+y))). + rewrite <- (ring_opp_def x). + rewrite <- (ring_add_0_l (x + - x + - (x + y))). + rewrite <- (ring_opp_def y). + rewrite (ring_add_comm x). + rewrite (ring_add_comm y). + rewrite <- (ring_add_assoc (-y)). + rewrite <- (ring_add_assoc (- x)). + rewrite (ring_add_assoc y). + rewrite (ring_add_comm y). + rewrite <- (ring_add_assoc (- x)). + rewrite (ring_add_assoc y). + rewrite (ring_add_comm y);rewrite ring_opp_def . + rewrite (ring_add_comm (-x) 0);rewrite ring_add_0_l . + rewrite ring_add_comm; reflexivity. + Qed. + + Lemma ring_opp_opp : forall x, - -x == x. + Proof. + intros x; rewrite <- (ring_add_0_l (- -x)). + rewrite <- (ring_opp_def x). + rewrite <- ring_add_assoc ; rewrite ring_opp_def . + rewrite (ring_add_comm x); rewrite ring_add_0_l . reflexivity. + Qed. + + Lemma ring_sub_ext : + forall x1 x2, x1 == x2 -> forall y1 y2, y1 == y2 -> x1 - y1 == x2 - y2. + Proof. + intros. + setoid_replace (x1 - y1) with (x1 + -y1). + setoid_replace (x2 - y2) with (x2 + -y2). + rewrite H;rewrite H0;reflexivity. + rewrite ring_sub_def. reflexivity. + rewrite ring_sub_def. reflexivity. + Qed. + + Ltac mrewrite := + repeat first + [ rewrite ring_add_0_l + | rewrite <- (ring_add_comm 0) + | rewrite ring_mul_1_l + | rewrite ring_mul_0_l + | rewrite ring_distr_l + | reflexivity + ]. + + Lemma ring_add_0_r : forall x, (x + 0) == x. + Proof. intros; mrewrite. Qed. + + + Lemma ring_add_assoc1 : forall x y z, (x + y) + z == (y + z) + x. + Proof. + intros;rewrite <- (ring_add_assoc x). + rewrite (ring_add_comm x);reflexivity. + Qed. + + Lemma ring_add_assoc2 : forall x y z, (y + x) + z == (y + z) + x. + Proof. + intros; repeat rewrite <- ring_add_assoc. + rewrite (ring_add_comm x); reflexivity. + Qed. + + Lemma ring_opp_zero : -0 == 0. + Proof. + rewrite <- (ring_mul_0_r 0). rewrite ring_opp_mul_l. + repeat rewrite ring_mul_0_r. reflexivity. + Qed. + +End Ring. + +(** Some simplification tactics*) +Ltac gen_reflexivity := reflexivity. + +Ltac gen_rewrite := + repeat first + [ reflexivity + | progress rewrite ring_opp_zero + | rewrite ring_add_0_l + | rewrite ring_add_0_r + | rewrite ring_mul_1_l + | rewrite ring_mul_1_r + | rewrite ring_mul_0_l + | rewrite ring_mul_0_r + | rewrite ring_distr_l + | rewrite ring_distr_r + | rewrite ring_add_assoc + | rewrite ring_mul_assoc + | progress rewrite ring_opp_add + | progress rewrite ring_sub_def + | progress rewrite <- ring_opp_mul_l + | progress rewrite <- ring_opp_mul_r ]. + +Ltac gen_add_push x := +repeat (match goal with + | |- context [(?y + x) + ?z] => + progress rewrite (ring_add_assoc2 x y z) + | |- context [(x + ?y) + ?z] => + progress rewrite (ring_add_assoc1 x y z) + end). |