set "baseuri" "cic:/matita/integration_algebras/".
-include "higher_order_defs/functions.ma".
-include "nat/nat.ma".
-include "nat/orders.ma".
-
-definition left_neutral \def λC,op.λe:C. ∀x:C. op e x = x.
-
-definition left_inverse \def λC,op.λe:C.λinv:C→C. ∀x:C. op (inv x) x = e.
-
-definition distributive_right ≝
- λA:Type.λf:A→A→A.λg:A→A→A.
- ∀x,y,z. f (g x y) z = g (f x z) (f y z).
-
-record is_abelian_group (C:Type) (plus:C→C→C) (zero:C) (opp:C→C) : Prop \def
- { (* abelian additive semigroup properties *)
- plus_assoc: associative ? plus;
- plus_comm: symmetric ? plus;
- (* additive monoid properties *)
- zero_neutral: left_neutral ? plus zero;
- (* additive group properties *)
- opp_inverse: left_inverse ? plus zero opp
- }.
+include "vector_spaces.ma".
+include "lattices.ma".
-record is_ring (C:Type) (plus:C→C→C) (mult:C→C→C) (zero:C) (opp:C→C) : Prop
-≝
- { (* abelian group properties *)
- abelian_group:> is_abelian_group ? plus zero opp;
- (* multiplicative semigroup properties *)
- mult_assoc: associative ? mult;
- (* ring properties *)
- mult_plus_distr_left: distributive ? mult plus;
- mult_plus_distr_right: distributive_right C mult plus
- }.
-
-record ring : Type \def
- { r_carrier:> Type;
- r_plus: r_carrier → r_carrier → r_carrier;
- r_mult: r_carrier → r_carrier → r_carrier;
- r_zero: r_carrier;
- r_opp: r_carrier → r_carrier;
- r_ring_properties:> is_ring ? r_plus r_mult r_zero r_opp
+(**************** Riesz Spaces ********************)
+
+record is_riesz_space (K:ordered_field_ch0) (V:vector_space K)
+ (L:lattice V)
+: Prop
+\def
+ { rs_compat_le_plus: ∀f,g,h:V. os_le ? L f g → os_le ? L (f+h) (g+h);
+ rs_compat_le_times: ∀a:K.∀f:V. zero K≤a → os_le ? L (zero V) f → os_le ? L (zero V) (a*f)
}.
-notation "0" with precedence 89
-for @{ 'zero }.
+record riesz_space (K:ordered_field_ch0) : Type \def
+ { rs_vector_space:> vector_space K;
+ rs_lattice:> lattice rs_vector_space;
+ rs_riesz_space_properties: is_riesz_space ? rs_vector_space rs_lattice
+ }.
-interpretation "Ring zero" 'zero =
- (cic:/matita/integration_algebras/r_zero.con _).
+record is_positive_linear (K) (V:riesz_space K) (T:V→K) : Prop ≝
+ { positive: ∀u:V. os_le ? V 0 u → os_le ? K 0 (T u);
+ linear1: ∀u,v:V. T (u+v) = T u + T v;
+ linear2: ∀u:V.∀k:K. T (k*u) = k*(T u)
+ }.
-interpretation "Ring plus" 'plus a b =
- (cic:/matita/integration_algebras/r_plus.con _ a b).
+record sequentially_order_continuous (K) (V:riesz_space K) (T:V→K) : Prop ≝
+ { soc_incr:
+ ∀a:nat→V.∀l:V.is_increasing ? ? a → is_sup ? V a l →
+ is_increasing ? K (λn.T (a n)) ∧ tends_to ? (λn.T (a n)) (T l)
+ }.
-interpretation "Ring mult" 'times a b =
- (cic:/matita/integration_algebras/r_mult.con _ a b).
+definition absolute_value \def λK.λS:riesz_space K.λf.join ? S f (-f).
-interpretation "Ring opp" 'uminus a =
- (cic:/matita/integration_algebras/r_opp.con _ a).
+(**************** Normed Riesz spaces ****************************)
-lemma eq_mult_zero_x_zero: ∀R:ring.∀x:R.0*x=0.
- intros;
- generalize in match (zero_neutral ? ? ? ? R 0); intro;
- generalize in match (eq_f ? ? (λy.y*x) ? ? H); intro; clear H;
- rewrite > (mult_plus_distr_right ? ? ? ? ? R) in H1;
- generalize in match (eq_f ? ? (λy.-(0*x)+y) ? ? H1); intro; clear H1;
- rewrite < (plus_assoc ? ? ? ? R) in H;
- rewrite > (opp_inverse ? ? ? ? R) in H;
- rewrite > (zero_neutral ? ? ? ? R) in H;
- assumption.
-qed.
+definition is_riesz_norm ≝
+ λR:real.λV:riesz_space R.λnorm:norm R V.
+ ∀f,g:V. os_le ? V (absolute_value ? V f) (absolute_value ? V g) →
+ os_le ? R (n_function R V norm f) (n_function R V norm g).
-record is_field (C:Type) (plus:C→C→C) (mult:C→C→C) (zero,one:C) (opp:C→C)
- (inv:∀x:C.x ≠ zero →C) : Prop
-≝
- { (* ring properties *)
- ring_properties: is_ring ? plus mult zero opp;
- (* multiplicative abelian properties *)
- mult_comm: symmetric ? mult;
- (* multiplicative monoid properties *)
- one_neutral: left_neutral ? mult one;
- (* multiplicative group properties *)
- inv_inverse: ∀x.∀p: x ≠ zero. mult (inv x p) x = one;
- (* integral domain *)
- not_eq_zero_one: zero ≠ one
+record riesz_norm (R:real) (V:riesz_space R) : Type ≝
+ { rn_norm:> norm R V;
+ rn_riesz_norm_property: is_riesz_norm ? ? rn_norm
}.
-let rec sum (C:Type) (plus:C→C→C) (zero,one:C) (n:nat) on n ≝
- match n with
- [ O ⇒ zero
- | (S m) ⇒ plus one (sum C plus zero one m)
- ].
+(*CSC: non fa la chiusura delle coercion verso funclass *)
+definition rn_function ≝
+ λR:real.λV:riesz_space R.λnorm:riesz_norm ? V.
+ n_function R V (rn_norm ? ? norm).
+
+coercion cic:/matita/integration_algebras/rn_function.con 1.
-record field : Type \def
- { f_ring:> ring;
- one: f_ring;
- inv: ∀x:f_ring. x ≠ 0 → f_ring;
- field_properties:
- is_field ? (r_plus f_ring) (r_mult f_ring) (r_zero f_ring) one
- (r_opp f_ring) inv
+(************************** L-SPACES *************************************)
+(*
+record is_l_space (R:real) (V:riesz_space R) (norm:riesz_norm ? V) : Prop ≝
+ { ls_banach: is_complete ? V (induced_distance ? ? norm);
+ ls_linear: ∀f,g:V. le ? V 0 f → le ? V 0 g → norm (f+g) = norm f + norm g
}.
+*)
+(******************** ARCHIMEDEAN RIESZ SPACES ***************************)
+
+record is_archimedean_riesz_space (K) (S:riesz_space K) : Prop
+\def
+ { ars_archimedean: ∃u:S.∀n.∀a.∀p:n > O.
+ os_le ? S
+ (absolute_value ? S a)
+ ((inv K (sum_field K n) (not_eq_sum_field_zero K n p))* u) →
+ a = 0
+ }.
-definition sum_field ≝
- λF:field. sum ? (r_plus F) (r_zero F) (one F).
-
-notation "1" with precedence 89
-for @{ 'one }.
-
-interpretation "Field one" 'one =
- (cic:/matita/integration_algebras/one.con _).
-
-record is_ordered_field_ch0 (C:Type) (plus,mult:C→C→C) (zero,one:C) (opp:C→C)
- (inv:∀x:C.x ≠ zero → C) (le:C→C→Prop) : Prop \def
- { (* field properties *)
- of_is_field:> is_field C plus mult zero one opp inv;
- of_mult_compat: ∀a,b. le zero a → le zero b → le zero (mult a b);
- of_plus_compat: ∀a,b,c. le a b → le (plus a c) (plus b c);
- of_weak_tricotomy : ∀a,b. a≠b → le a b ∨ le b a;
- (* 0 characteristics *)
- of_char0: ∀n. n > O → sum ? plus zero one n ≠ zero
+record archimedean_riesz_space (K:ordered_field_ch0) : Type \def
+ { ars_riesz_space:> riesz_space K;
+ ars_archimedean_property: is_archimedean_riesz_space ? ars_riesz_space
}.
-
-record ordered_field_ch0 : Type \def
- { of_field:> field;
- of_le: of_field → of_field → Prop;
- of_ordered_field_properties:>
- is_ordered_field_ch0 ? (r_plus of_field) (r_mult of_field) (r_zero of_field)
- (one of_field) (r_opp of_field) (inv of_field) of_le
+
+definition is_weak_unit ≝
+(* This definition is by Spitters. He cites Fremlin 353P, but:
+ 1. that theorem holds only in f-algebras (as in Spitters, but we are
+ defining it on Riesz spaces)
+ 2. Fremlin proves |x|/\u=0 \to u=0. How do we remove the absolute value?
+ λR:real.λV:archimedean_riesz_space R.λunit: V.
+ ∀x:V. meet x unit = 0 → u = 0.
+ 3. Fremlin proves u > 0 implies x /\ u > 0 > 0 for Archimedean spaces
+ only. We pick this definition for now.
+*) λR:real.λV:archimedean_riesz_space R.λe:V.
+ ∀v:V. lt ? V 0 v → lt ? V 0 (meet ? V v e).
+
+(* Here we are avoiding a construction (the quotient space to define
+ f=g iff I(|f-g|)=0 *)
+record integration_riesz_space (R:real) : Type \def
+ { irs_archimedean_riesz_space:> archimedean_riesz_space R;
+ irs_unit: irs_archimedean_riesz_space;
+ irs_weak_unit: is_weak_unit ? ? irs_unit;
+ integral: irs_archimedean_riesz_space → R;
+ irs_positive_linear: is_positive_linear ? ? integral;
+ irs_limit1:
+ ∀f:irs_archimedean_riesz_space.
+ tends_to ?
+ (λn.integral (meet ? irs_archimedean_riesz_space f
+ ((sum_field R n)*irs_unit)))
+ (integral f);
+ irs_limit2:
+ ∀f:irs_archimedean_riesz_space.
+ tends_to ?
+ (λn.
+ integral (meet ? irs_archimedean_riesz_space f
+ ((inv ? (sum_field R (S n))
+ (not_eq_sum_field_zero R (S n) (le_S_S O n (le_O_n n)))
+ ) * irs_unit))) 0;
+ irs_quotient_space1:
+ ∀f,g:irs_archimedean_riesz_space.
+ integral (absolute_value ? irs_archimedean_riesz_space (f - g)) = 0 → f=g
}.
-interpretation "Ordered field le" 'leq a b =
- (cic:/matita/integration_algebras/of_le.con _ a b).
-
-definition lt \def λF:ordered_field_ch0.λa,b:F.a ≤ b ∧ a ≠ b.
-
-interpretation "Ordered field lt" 'lt a b =
- (cic:/matita/integration_algebras/lt.con _ a b).
-
-axiom le_zero_x_to_le_opp_x_zero: ∀F:ordered_field_ch0.∀x:F. 0 ≤ x → -x ≤ 0.
-(* intros;
- generalize in match (of_plus_compat ? ? ? ? ? ? ? ? F ? ? (-x) H); intro;
- rewrite > (zero_neutral ? ? ? ? F) in H1;
- rewrite > (plus_comm ? ? ? ? F) in H1;
- rewrite > (opp_inverse ? ? ? ? F) in H1;
- assumption.
-qed.*)
+definition induced_norm_fun ≝
+ λR:real.λV:integration_riesz_space R.λf:V.
+ integral ? V (absolute_value ? ? f).
-axiom le_x_zero_to_le_zero_opp_x: ∀F:ordered_field_ch0.∀x:F. x ≤ 0 → 0 ≤ -x.
-(* intros;
- generalize in match (of_plus_compat ? ? ? ? ? ? ? ? F ? ? (-x) H); intro;
- rewrite > (zero_neutral ? ? ? ? F) in H1;
- rewrite > (plus_comm ? ? ? ? F) in H1;
- rewrite > (opp_inverse ? ? ? ? F) in H1;
- assumption.
-qed.*)
+lemma induced_norm_is_norm:
+ ∀R:real.∀V:integration_riesz_space R.is_norm R V (induced_norm_fun ? V).
+ elim daemon.(*
+ intros;
+ apply mk_is_norm;
+ [ apply mk_is_semi_norm;
+ [ unfold induced_norm_fun;
+ intros;
+ apply positive;
+ [ apply (irs_positive_linear ? V)
+ | (* difficile *)
+ elim daemon
+ ]
+ | intros;
+ unfold induced_norm_fun;
+ (* facile *)
+ elim daemon
+ | intros;
+ unfold induced_norm_fun;
+ (* difficile *)
+ elim daemon
+ ]
+ | intros;
+ unfold induced_norm_fun in H;
+ apply irs_quotient_space1;
+ unfold minus;
+ rewrite < plus_comm;
+ rewrite < eq_zero_opp_zero;
+ rewrite > zero_neutral;
+ assumption
+ ].*)
+qed.
-(*
-lemma eq_opp_x_times_opp_one_x: ∀F:ordered_field_ch0.∀x:F.-x = -1*x.
+definition induced_norm ≝
+ λR:real.λV:integration_riesz_space R.
+ mk_norm ? ? (induced_norm_fun ? V) (induced_norm_is_norm ? V).
+
+lemma is_riesz_norm_induced_norm:
+ ∀R:real.∀V:integration_riesz_space R.
+ is_riesz_norm ? ? (induced_norm ? V).
intros;
-
-lemma not_eq_x_zero_to_lt_zero_mult_x_x:
- ∀F:ordered_field_ch0.∀x:F. x ≠ 0 → 0 < x * x.
+ unfold is_riesz_norm;
intros;
- elim (of_weak_tricotomy ? ? ? ? ? ? ? ? F ? ? H);
- [ generalize in match (le_x_zero_to_le_zero_opp_x F ? H1); intro;
- generalize in match (of_mult_compat ? ? ? ? ? ? ? ? F ? ? H2 H2); intro;
-*)
+ unfold induced_norm;
+ simplify;
+ unfold induced_norm_fun;
+ (* difficile *)
+ elim daemon.
+qed.
-axiom not_eq_sum_field_zero: ∀F,n. n > O → sum_field F n ≠ 0.
+definition induced_riesz_norm ≝
+ λR:real.λV:integration_riesz_space R.
+ mk_riesz_norm ? ? (induced_norm ? V) (is_riesz_norm_induced_norm ? V).
-record is_vector_space (K: field) (C:Type) (plus:C→C→C) (zero:C) (opp:C→C)
- (emult:K→C→C) : Prop
-≝
- { (* abelian group properties *)
- vs_abelian_group: is_abelian_group ? plus zero opp;
- (* other properties *)
- vs_nilpotent: ∀v. emult 0 v = zero;
- vs_neutral: ∀v. emult 1 v = v;
- vs_distributive: ∀a,b,v. emult (a + b) v = plus (emult a v) (emult b v);
- vs_associative: ∀a,b,v. emult (a * b) v = emult a (emult b v)
- }.
+definition distance_induced_by_integral ≝
+ λR:real.λV:integration_riesz_space R.
+ induced_distance ? ? (induced_norm R V).
-record is_lattice (C:Type) (join,meet:C→C→C) : Prop \def
- { (* abelian semigroup properties *)
- l_comm_j: symmetric ? join;
- l_associative_j: associative ? join;
- l_comm_m: symmetric ? meet;
- l_associative_m: associative ? meet;
- (* other properties *)
- l_adsorb_j_m: ∀f,g. join f (meet f g) = f;
- l_adsorb_m_j: ∀f,g. meet f (join f g) = f
- }.
+definition is_complete_integration_riesz_space ≝
+ λR:real.λV:integration_riesz_space R.
+ is_complete ? ? (distance_induced_by_integral ? V).
-definition le \def λC.λmeet:C→C→C.λf,g. meet f g = f.
-
-record is_riesz_space (K:ordered_field_ch0) (C:Type) (plus:C→C→C) (zero:C)
- (opp:C→C) (emult:K→C→C) (join,meet:C→C→C) : Prop \def
- { (* vector space properties *)
- rs_vector_space: is_vector_space K C plus zero opp emult;
- (* lattice properties *)
- rs_lattice: is_lattice C join meet;
- (* other properties *)
- rs_compat_le_plus: ∀f,g,h. le ? meet f g →le ? meet (plus f h) (plus g h);
- rs_compat_le_times: ∀a,f. 0≤a → le ? meet zero f → le ? meet zero (emult a f)
+record complete_integration_riesz_space (R:real) : Type ≝
+ { cirz_integration_riesz_space:> integration_riesz_space R;
+ cirz_complete_integration_riesz_space_property:
+ is_complete_integration_riesz_space ? cirz_integration_riesz_space
}.
-definition absolute_value \def λC:Type.λopp.λjoin:C→C→C.λf.join f (opp f).
+(* now we prove that any complete integration riesz space is an L-space *)
-record is_archimedean_riesz_space (K:ordered_field_ch0) (C:Type) (plus:C→C→C)
- (zero:C) (opp:C→C) (mult:Type_OF_ordered_field_ch0 K→C→C) (join,meet:C→C→C)
- :Prop \def
- { ars_riesz_space: is_riesz_space ? ? plus zero opp mult join meet;
- ars_archimedean: ∃u.∀n,a.∀p:n > O.
- le C meet (absolute_value ? opp join a)
- (mult (inv K (sum_field K n) (not_eq_sum_field_zero K n p)) u) →
- a = zero
- }.
+(*theorem is_l_space_l_space_induced_by_integral:
+ ∀R:real.∀V:complete_integration_riesz_space R.
+ is_l_space ? ? (induced_riesz_norm ? V).
+ intros;
+ constructor 1;
+ [ apply cirz_complete_integration_riesz_space_property
+ | intros;
+ unfold induced_riesz_norm;
+ simplify;
+ unfold induced_norm;
+ simplify;
+ unfold induced_norm_fun;
+ (* difficile *)
+ elim daemon
+ ].
+qed.*)
-record is_algebra (K: field) (C:Type) (plus:C→C→C) (zero:C) (opp:C→C)
- (emult:K→C→C) (mult:C→C→C) : Prop
+(**************************** f-ALGEBRAS ********************************)
+
+record is_algebra (K: field) (V:vector_space K) (mult:V→V→V) (one:V) : Prop
≝
- { (* vector space properties *)
- a_vector_space_properties: is_vector_space ? ? plus zero opp emult;
- (* ring properties *)
- a_ring: is_ring ? plus mult zero opp;
+ { (* ring properties *)
+ a_ring: is_ring V mult one;
(* algebra properties *)
- a_associative_left: ∀a,f,g. emult a (mult f g) = mult (emult a f) g;
- a_associative_right: ∀a,f,g. emult a (mult f g) = mult f (emult a g)
- }.
\ No newline at end of file
+ a_associative_left: ∀a,f,g. a * (mult f g) = mult (a * f) g;
+ a_associative_right: ∀a,f,g. a * (mult f g) = mult f (a * g)
+ }.
+
+record algebra (K: field) (V:vector_space K) (a_one:V) : Type \def
+ { a_mult: V → V → V;
+ a_algebra_properties: is_algebra ? ? a_mult a_one
+ }.
+
+interpretation "Algebra product" 'times a b =
+ (cic:/matita/integration_algebras/a_mult.con _ _ _ a b).
+
+definition ring_of_algebra ≝
+ λK.λV:vector_space K.λone:V.λA:algebra ? V one.
+ mk_ring V (a_mult ? ? ? A) one
+ (a_ring ? ? ? ? (a_algebra_properties ? ? ? A)).
+
+coercion cic:/matita/integration_algebras/ring_of_algebra.con.
+
+record is_f_algebra (K) (S:archimedean_riesz_space K) (one: S)
+ (A:algebra ? S one) : Prop
+\def
+{ compat_mult_le:
+ ∀f,g:S.
+ le ? S 0 f → le ? S 0 g → le ? S 0 (a_mult ? ? ? A f g);
+ compat_mult_meet:
+ ∀f,g,h:S.
+ meet ? S f g = 0 → meet ? S (a_mult ? ? ? A h f) g = 0
+}.
+
+record f_algebra (K:ordered_field_ch0) (R:archimedean_riesz_space K) (one:R) :
+Type \def
+{ fa_algebra:> algebra ? R one;
+ fa_f_algebra_properties: is_f_algebra ? ? ? fa_algebra
+}.
+
+(* to be proved; see footnote 2 in the paper by Spitters *)
+axiom symmetric_a_mult:
+ ∀K,R,one.∀A:f_algebra K R one. symmetric ? (a_mult ? ? ? A).
+
+record integration_f_algebra (R:real) : Type \def
+ { ifa_integration_riesz_space:> integration_riesz_space R;
+ ifa_f_algebra:>
+ f_algebra ? ifa_integration_riesz_space
+ (irs_unit ? ifa_integration_riesz_space)
+ }.