1 (**************************************************************************)
4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
10 (* \ / This file is distributed under the terms of the *)
11 (* v GNU General Public License Version 2 *)
13 (**************************************************************************)
15 set "baseuri" "cic:/matita/integration_algebras/".
17 include "higher_order_defs/functions.ma".
19 include "nat/orders.ma".
21 definition left_neutral \def λC,op.λe:C. ∀x:C. op e x = x.
23 definition left_inverse \def λC,op.λe:C.λinv:C→C. ∀x:C. op (inv x) x = e.
25 definition distributive_right ≝
26 λA:Type.λf:A→A→A.λg:A→A→A.
27 ∀x,y,z. f (g x y) z = g (f x z) (f y z).
29 record is_abelian_group (C:Type) (plus:C→C→C) (zero:C) (opp:C→C) : Prop \def
30 { (* abelian additive semigroup properties *)
31 plus_assoc: associative ? plus;
32 plus_comm: symmetric ? plus;
33 (* additive monoid properties *)
34 zero_neutral: left_neutral ? plus zero;
35 (* additive group properties *)
36 opp_inverse: left_inverse ? plus zero opp
39 record is_ring (C:Type) (plus:C→C→C) (mult:C→C→C) (zero:C) (opp:C→C) : Prop
41 { (* abelian group properties *)
42 abelian_group:> is_abelian_group ? plus zero opp;
43 (* multiplicative semigroup properties *)
44 mult_assoc: associative ? mult;
46 mult_plus_distr_left: distributive ? mult plus;
47 mult_plus_distr_right: distributive_right C mult plus
50 record ring : Type \def
52 r_plus: r_carrier → r_carrier → r_carrier;
53 r_mult: r_carrier → r_carrier → r_carrier;
55 r_opp: r_carrier → r_carrier;
56 r_ring_properties:> is_ring ? r_plus r_mult r_zero r_opp
59 notation "0" with precedence 89
62 interpretation "Ring zero" 'zero =
63 (cic:/matita/integration_algebras/r_zero.con _).
65 interpretation "Ring plus" 'plus a b =
66 (cic:/matita/integration_algebras/r_plus.con _ a b).
68 interpretation "Ring mult" 'times a b =
69 (cic:/matita/integration_algebras/r_mult.con _ a b).
71 interpretation "Ring opp" 'uminus a =
72 (cic:/matita/integration_algebras/r_opp.con _ a).
74 lemma eq_mult_zero_x_zero: ∀R:ring.∀x:R.0*x=0.
76 generalize in match (zero_neutral ? ? ? ? R 0); intro;
77 generalize in match (eq_f ? ? (λy.y*x) ? ? H); intro; clear H;
78 rewrite > (mult_plus_distr_right ? ? ? ? ? R) in H1;
79 generalize in match (eq_f ? ? (λy.-(0*x)+y) ? ? H1); intro; clear H1;
80 rewrite < (plus_assoc ? ? ? ? R) in H;
81 rewrite > (opp_inverse ? ? ? ? R) in H;
82 rewrite > (zero_neutral ? ? ? ? R) in H;
86 record is_field (C:Type) (plus:C→C→C) (mult:C→C→C) (zero,one:C) (opp:C→C)
87 (inv:∀x:C.x ≠ zero →C) : Prop
89 { (* ring properties *)
90 ring_properties: is_ring ? plus mult zero opp;
91 (* multiplicative abelian properties *)
92 mult_comm: symmetric ? mult;
93 (* multiplicative monoid properties *)
94 one_neutral: left_neutral ? mult one;
95 (* multiplicative group properties *)
96 inv_inverse: ∀x.∀p: x ≠ zero. mult (inv x p) x = one;
98 not_eq_zero_one: zero ≠ one
101 let rec sum (C:Type) (plus:C→C→C) (zero,one:C) (n:nat) on n ≝
104 | (S m) ⇒ plus one (sum C plus zero one m)
107 record field : Type \def
110 inv: ∀x:f_ring. x ≠ 0 → f_ring;
112 is_field ? (r_plus f_ring) (r_mult f_ring) (r_zero f_ring) one
116 definition sum_field ≝
117 λF:field. sum ? (r_plus F) (r_zero F) (one F).
119 notation "1" with precedence 89
122 interpretation "Field one" 'one =
123 (cic:/matita/integration_algebras/one.con _).
125 record is_ordered_field_ch0 (C:Type) (plus,mult:C→C→C) (zero,one:C) (opp:C→C)
126 (inv:∀x:C.x ≠ zero → C) (le:C→C→Prop) : Prop \def
127 { (* field properties *)
128 of_is_field:> is_field C plus mult zero one opp inv;
129 of_mult_compat: ∀a,b. le zero a → le zero b → le zero (mult a b);
130 of_plus_compat: ∀a,b,c. le a b → le (plus a c) (plus b c);
131 of_weak_tricotomy : ∀a,b. a≠b → le a b ∨ le b a;
132 (* 0 characteristics *)
133 of_char0: ∀n. n > O → sum ? plus zero one n ≠ zero
136 record ordered_field_ch0 : Type \def
138 of_le: of_field → of_field → Prop;
139 of_ordered_field_properties:>
140 is_ordered_field_ch0 ? (r_plus of_field) (r_mult of_field) (r_zero of_field)
141 (one of_field) (r_opp of_field) (inv of_field) of_le
144 interpretation "Ordered field le" 'leq a b =
145 (cic:/matita/integration_algebras/of_le.con _ a b).
147 definition lt \def λF:ordered_field_ch0.λa,b:F.a ≤ b ∧ a ≠ b.
149 interpretation "Ordered field lt" 'lt a b =
150 (cic:/matita/integration_algebras/lt.con _ a b).
152 axiom le_zero_x_to_le_opp_x_zero: ∀F:ordered_field_ch0.∀x:F. 0 ≤ x → -x ≤ 0.
154 generalize in match (of_plus_compat ? ? ? ? ? ? ? ? F ? ? (-x) H); intro;
155 rewrite > (zero_neutral ? ? ? ? F) in H1;
156 rewrite > (plus_comm ? ? ? ? F) in H1;
157 rewrite > (opp_inverse ? ? ? ? F) in H1;
161 axiom le_x_zero_to_le_zero_opp_x: ∀F:ordered_field_ch0.∀x:F. x ≤ 0 → 0 ≤ -x.
163 generalize in match (of_plus_compat ? ? ? ? ? ? ? ? F ? ? (-x) H); intro;
164 rewrite > (zero_neutral ? ? ? ? F) in H1;
165 rewrite > (plus_comm ? ? ? ? F) in H1;
166 rewrite > (opp_inverse ? ? ? ? F) in H1;
171 lemma eq_opp_x_times_opp_one_x: ∀F:ordered_field_ch0.∀x:F.-x = -1*x.
174 lemma not_eq_x_zero_to_lt_zero_mult_x_x:
175 ∀F:ordered_field_ch0.∀x:F. x ≠ 0 → 0 < x * x.
177 elim (of_weak_tricotomy ? ? ? ? ? ? ? ? F ? ? H);
178 [ generalize in match (le_x_zero_to_le_zero_opp_x F ? H1); intro;
179 generalize in match (of_mult_compat ? ? ? ? ? ? ? ? F ? ? H2 H2); intro;
182 axiom not_eq_sum_field_zero: ∀F,n. n > O → sum_field F n ≠ 0.
184 record is_vector_space (K: field) (C:Type) (plus:C→C→C) (zero:C) (opp:C→C)
187 { (* abelian group properties *)
188 vs_abelian_group: is_abelian_group ? plus zero opp;
189 (* other properties *)
190 vs_nilpotent: ∀v. emult 0 v = zero;
191 vs_neutral: ∀v. emult 1 v = v;
192 vs_distributive: ∀a,b,v. emult (a + b) v = plus (emult a v) (emult b v);
193 vs_associative: ∀a,b,v. emult (a * b) v = emult a (emult b v)
196 record is_lattice (C:Type) (join,meet:C→C→C) : Prop \def
197 { (* abelian semigroup properties *)
198 l_comm_j: symmetric ? join;
199 l_associative_j: associative ? join;
200 l_comm_m: symmetric ? meet;
201 l_associative_m: associative ? meet;
202 (* other properties *)
203 l_adsorb_j_m: ∀f,g. join f (meet f g) = f;
204 l_adsorb_m_j: ∀f,g. meet f (join f g) = f
207 definition le \def λC.λmeet:C→C→C.λf,g. meet f g = f.
209 record is_riesz_space (K:ordered_field_ch0) (C:Type) (plus:C→C→C) (zero:C)
210 (opp:C→C) (emult:K→C→C) (join,meet:C→C→C) : Prop \def
211 { (* vector space properties *)
212 rs_vector_space: is_vector_space K C plus zero opp emult;
213 (* lattice properties *)
214 rs_lattice: is_lattice C join meet;
215 (* other properties *)
216 rs_compat_le_plus: ∀f,g,h. le ? meet f g →le ? meet (plus f h) (plus g h);
217 rs_compat_le_times: ∀a,f. 0≤a → le ? meet zero f → le ? meet zero (emult a f)
220 definition absolute_value \def λC:Type.λopp.λjoin:C→C→C.λf.join f (opp f).
222 record is_archimedean_riesz_space (K:ordered_field_ch0) (C:Type) (plus:C→C→C)
223 (zero:C) (opp:C→C) (mult:Type_OF_ordered_field_ch0 K→C→C) (join,meet:C→C→C)
225 { ars_riesz_space: is_riesz_space ? ? plus zero opp mult join meet;
226 ars_archimedean: ∃u.∀n,a.∀p:n > O.
227 le C meet (absolute_value ? opp join a)
228 (mult (inv K (sum_field K n) (not_eq_sum_field_zero K n p)) u) →
232 record is_algebra (K: field) (C:Type) (plus:C→C→C) (zero:C) (opp:C→C)
233 (emult:K→C→C) (mult:C→C→C) : Prop
235 { (* vector space properties *)
236 a_vector_space_properties: is_vector_space ? ? plus zero opp emult;
237 (* ring properties *)
238 a_ring: is_ring ? plus mult zero opp;
239 (* algebra properties *)
240 a_associative_left: ∀a,f,g. emult a (mult f g) = mult (emult a f) g;
241 a_associative_right: ∀a,f,g. emult a (mult f g) = mult f (emult a g)