--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||M|| *)
+(* ||A|| A project by Andrea Asperti *)
+(* ||T|| *)
+(* ||I|| Developers: *)
+(* ||T|| The HELM team. *)
+(* ||A|| http://helm.cs.unibo.it *)
+(* \ / *)
+(* \ / This file is distributed under the terms of the *)
+(* v GNU General Public License Version 2 *)
+(* *)
+(**************************************************************************)
+
+
+
+include "attic/vector_spaces.ma".
+include "lattice.ma".
+
+(**************** Riesz Spaces ********************)
+
+record pre_riesz_space (K:ordered_field_ch0) : Type \def
+ { rs_vector_space:> vector_space K;
+ rs_lattice_: lattice;
+ rs_ordered_abelian_group_: ordered_abelian_group;
+ rs_with1:
+ og_abelian_group rs_ordered_abelian_group_ = vs_abelian_group ? rs_vector_space;
+ rs_with2:
+ og_ordered_set rs_ordered_abelian_group_ = ordered_set_of_lattice rs_lattice_
+ }.
+
+lemma rs_lattice: ∀K.pre_riesz_space K → lattice.
+ intros (K V);
+ cut (os_carrier (rs_lattice_ ? V) = V);
+ [ apply mk_lattice;
+ [ apply (carrier V)
+ | apply (eq_rect ? ? (λC:Type.C→C→C) ? ? Hcut);
+ apply l_join
+ | apply (eq_rect ? ? (λC:Type.C→C→C) ? ? Hcut);
+ apply l_meet
+ | apply
+ (eq_rect' ? ?
+ (λa:Type.λH:os_carrier (rs_lattice_ ? V)=a.
+ is_lattice a
+ (eq_rect Type (rs_lattice_ K V) (λC:Type.C→C→C)
+ (l_join (rs_lattice_ K V)) a H)
+ (eq_rect Type (rs_lattice_ K V) (λC:Type.C→C→C)
+ (l_meet (rs_lattice_ K V)) a H))
+ ? ? Hcut);
+ simplify;
+ apply l_lattice_properties
+ ]
+ | transitivity (os_carrier (rs_ordered_abelian_group_ ? V));
+ [ apply (eq_f ? ? os_carrier);
+ symmetry;
+ apply rs_with2
+ | apply (eq_f ? ? carrier);
+ apply rs_with1
+ ]
+ ].
+qed.
+
+coercion cic:/matita/attic/integration_algebras/rs_lattice.con.
+
+lemma rs_ordered_abelian_group: ∀K.pre_riesz_space K → ordered_abelian_group.
+ intros (K V);
+ apply mk_ordered_abelian_group;
+ [ apply mk_pre_ordered_abelian_group;
+ [ apply (vs_abelian_group ? (rs_vector_space ? V))
+ | apply (ordered_set_of_lattice (rs_lattice ? V))
+ | reflexivity
+ ]
+ | simplify;
+ generalize in match
+ (og_ordered_abelian_group_properties (rs_ordered_abelian_group_ ? V));
+ intro P;
+ unfold in P;
+ elim daemon(*
+ apply
+ (eq_rect ? ?
+ (λO:ordered_set.
+ ∀f,g,h.
+ os_le O f g →
+ os_le O
+ (plus (abelian_group_OF_pre_riesz_space K V) f h)
+ (plus (abelian_group_OF_pre_riesz_space K V) g h))
+ ? ? (rs_with2 ? V));
+ apply
+ (eq_rect ? ?
+ (λG:abelian_group.
+ ∀f,g,h.
+ os_le (ordered_set_OF_pre_riesz_space K V) f g →
+ os_le (ordered_set_OF_pre_riesz_space K V)
+ (plus (abelian_group_OF_pre_riesz_space K V) f h)
+ (plus (abelian_group_OF_pre_riesz_space K V) g h))
+ ? ? (rs_with1 ? V));
+ simplify;
+ apply og_ordered_abelian_group_properties*)
+ ]
+qed.
+
+coercion cic:/matita/attic/integration_algebras/rs_ordered_abelian_group.con.
+
+record is_riesz_space (K:ordered_field_ch0) (V:pre_riesz_space K) : Prop ≝
+ { rs_compat_le_times: ∀a:K.∀f:V. 0≤a → 0≤f → 0≤a*f
+ }.
+
+record riesz_space (K:ordered_field_ch0) : Type \def
+ { rs_pre_riesz_space:> pre_riesz_space K;
+ rs_riesz_space_properties: is_riesz_space ? rs_pre_riesz_space
+ }.
+
+record is_positive_linear (K) (V:riesz_space K) (T:V→K) : Prop ≝
+ { positive: ∀u:V. 0≤u → 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)
+ }.
+
+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)
+ }.
+
+definition absolute_value ≝ λK.λS:riesz_space K.λf:S.f ∨ -f.
+
+(**************** Normed Riesz spaces ****************************)
+
+definition is_riesz_norm ≝
+ λR:real.λV:riesz_space R.λnorm:norm R V.
+ ∀f,g:V. absolute_value ? V f ≤ absolute_value ? V g →
+ n_function R V norm f ≤ n_function R V norm g.
+
+record riesz_norm (R:real) (V:riesz_space R) : Type ≝
+ { rn_norm:> norm R V;
+ rn_riesz_norm_property: is_riesz_norm ? ? rn_norm
+ }.
+
+(*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/attic/integration_algebras/rn_function.con 1.
+
+(************************** 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.
+ absolute_value ? S a ≤
+ (inv K (sum_field K n) (not_eq_sum_field_zero K n p))* u →
+ a = 0
+ }.
+
+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
+ }.
+
+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. 0<v → 0 < (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 (f ∧ ((sum_field R n)*irs_unit)))
+ (integral f);
+ irs_limit2:
+ ∀f:irs_archimedean_riesz_space.
+ tends_to ?
+ (λn.
+ integral (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
+ }.
+
+definition induced_norm_fun ≝
+ λR:real.λV:integration_riesz_space R.λf:V.
+ integral ? V (absolute_value ? ? f).
+
+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.
+
+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;
+ unfold is_riesz_norm;
+ intros;
+ unfold induced_norm;
+ simplify;
+ unfold induced_norm_fun;
+ (* difficile *)
+ elim daemon.
+qed.
+
+definition induced_riesz_norm ≝
+ λR:real.λV:integration_riesz_space R.
+ mk_riesz_norm ? ? (induced_norm ? V) (is_riesz_norm_induced_norm ? V).
+
+definition distance_induced_by_integral ≝
+ λR:real.λV:integration_riesz_space R.
+ induced_distance ? ? (induced_norm R V).
+
+definition is_complete_integration_riesz_space ≝
+ λR:real.λV:integration_riesz_space R.
+ is_complete ? ? (distance_induced_by_integral ? V).
+
+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
+ }.
+
+(* now we prove that any complete integration riesz space is an L-space *)
+
+(*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.*)
+
+(**************************** f-ALGEBRAS ********************************)
+
+record is_algebra (K: field) (V:vector_space K) (mult:V→V→V) (one:V) : Prop
+≝
+ { (* ring properties *)
+ a_ring: is_ring V mult one;
+ (* algebra properties *)
+ 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) : Type \def
+ { a_vector_space:> vector_space K;
+ a_one: a_vector_space;
+ a_mult: a_vector_space → a_vector_space → a_vector_space;
+ a_algebra_properties: is_algebra ? ? a_mult a_one
+ }.
+
+interpretation "Algebra product" 'times a b =
+ (cic:/matita/attic/integration_algebras/a_mult.con _ a b).
+
+definition ring_of_algebra ≝
+ λK.λA:algebra K.
+ mk_ring A (a_mult ? A) (a_one ? A)
+ (a_ring ? ? ? ? (a_algebra_properties ? A)).
+
+coercion cic:/matita/attic/integration_algebras/ring_of_algebra.con.
+
+record pre_f_algebra (K:ordered_field_ch0) : Type ≝
+ { fa_archimedean_riesz_space:> archimedean_riesz_space K;
+ fa_algebra_: algebra K;
+ fa_with: a_vector_space ? fa_algebra_ = rs_vector_space ? fa_archimedean_riesz_space
+ }.
+
+lemma fa_algebra: ∀K:ordered_field_ch0.pre_f_algebra K → algebra K.
+ intros (K A);
+ apply mk_algebra;
+ [ apply (rs_vector_space ? A)
+ | elim daemon
+ | elim daemon
+ | elim daemon
+ ]
+ qed.
+
+coercion cic:/matita/attic/integration_algebras/fa_algebra.con.
+
+record is_f_algebra (K) (A:pre_f_algebra K) : Prop ≝
+{ compat_mult_le: ∀f,g:A.0 ≤ f → 0 ≤ g → 0 ≤ f*g;
+ compat_mult_meet:
+ ∀f,g,h:A.(f ∧ g) = 0 → ((h*f) ∧ g) = 0
+}.
+
+record f_algebra (K:ordered_field_ch0) : Type ≝
+{ fa_pre_f_algebra:> pre_f_algebra K;
+ fa_f_algebra_properties: is_f_algebra ? fa_pre_f_algebra
+}.
+
+(* to be proved; see footnote 2 in the paper by Spitters *)
+axiom symmetric_a_mult:
+ ∀K.∀A:f_algebra K. 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 R;
+ ifa_with:
+ fa_archimedean_riesz_space ? ifa_f_algebra_ =
+ irs_archimedean_riesz_space ? ifa_integration_riesz_space
+ }.
+
+axiom ifa_f_algebra: ∀R:real.integration_f_algebra R → f_algebra R.
+
+coercion cic:/matita/attic/integration_algebras/ifa_f_algebra.con.
projects / helm.git / blobdiff