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/sequence/".
17 include "ordered_set.ma".
19 definition sequence := λO:pordered_set.nat → O.
21 definition fun_of_sequence: ∀O:pordered_set.sequence O → nat → O.
22 intros; apply s; assumption;
25 coercion cic:/matita/sequence/fun_of_sequence.con 1.
27 definition is_increasing ≝ λO:pordered_set.λa:sequence O.∀n:nat.a n ≤ a (S n).
28 definition is_decreasing ≝ λO:pordered_set.λa:sequence O.∀n:nat.a (S n) ≤ a n.
30 definition is_upper_bound ≝ λO:pordered_set.λa:sequence O.λu:O.∀n:nat.a n ≤ u.
31 definition is_lower_bound ≝ λO:pordered_set.λa:sequence O.λu:O.∀n:nat.u ≤ a n.
33 record is_sup (O:pordered_set) (a:sequence O) (u:O) : Prop ≝
34 { sup_upper_bound: is_upper_bound O a u;
35 sup_least_upper_bound: ∀v:O. is_upper_bound O a v → u≤v
38 record is_inf (O:pordered_set) (a:sequence O) (u:O) : Prop ≝
39 { inf_lower_bound: is_lower_bound O a u;
40 inf_greatest_lower_bound: ∀v:O. is_lower_bound O a v → v≤u
43 record is_bounded_below (O:pordered_set) (a:sequence O) : Type ≝
45 ib_lower_bound_is_lower_bound: is_lower_bound ? a ib_lower_bound
48 record is_bounded_above (O:pordered_set) (a:sequence O) : Type ≝
50 ib_upper_bound_is_upper_bound: is_upper_bound ? a ib_upper_bound
53 record is_bounded (O:pordered_set) (a:sequence O) : Type ≝
54 { ib_bounded_below:> is_bounded_below ? a;
55 ib_bounded_above:> is_bounded_above ? a
58 record bounded_below_sequence (O:pordered_set) : Type ≝
59 { bbs_seq:> sequence O;
60 bbs_is_bounded_below:> is_bounded_below ? bbs_seq
63 record bounded_above_sequence (O:pordered_set) : Type ≝
64 { bas_seq:> sequence O;
65 bas_is_bounded_above:> is_bounded_above ? bas_seq
68 record bounded_sequence (O:pordered_set) : Type ≝
69 { bs_seq:> sequence O;
70 bs_is_bounded_below: is_bounded_below ? bs_seq;
71 bs_is_bounded_above: is_bounded_above ? bs_seq
74 definition bounded_below_sequence_of_bounded_sequence ≝
75 λO:pordered_set.λb:bounded_sequence O.
76 mk_bounded_below_sequence ? b (bs_is_bounded_below ? b).
78 coercion cic:/matita/sequence/bounded_below_sequence_of_bounded_sequence.con.
80 definition bounded_above_sequence_of_bounded_sequence ≝
81 λO:pordered_set.λb:bounded_sequence O.
82 mk_bounded_above_sequence ? b (bs_is_bounded_above ? b).
84 coercion cic:/matita/sequence/bounded_above_sequence_of_bounded_sequence.con.
86 definition lower_bound ≝
87 λO:pordered_set.λb:bounded_below_sequence O.
88 ib_lower_bound ? b (bbs_is_bounded_below ? b).
90 lemma lower_bound_is_lower_bound:
91 ∀O:pordered_set.∀b:bounded_below_sequence O.
92 is_lower_bound ? b (lower_bound ? b).
93 intros; unfold lower_bound; apply ib_lower_bound_is_lower_bound.
96 definition upper_bound ≝
97 λO:pordered_set.λb:bounded_above_sequence O.
98 ib_upper_bound ? b (bas_is_bounded_above ? b).
100 lemma upper_bound_is_upper_bound:
101 ∀O:pordered_set.∀b:bounded_above_sequence O.
102 is_upper_bound ? b (upper_bound ? b).
103 intros; unfold upper_bound; apply ib_upper_bound_is_upper_bound.
106 definition reverse_excedence: excedence → excedence.
107 intros (E); apply (mk_excedence E); [apply (λx,y.exc_relation E y x)]
108 cases E (T f cRf cTf); simplify;
109 [1: unfold Not; intros (x H); apply (cRf x); assumption
110 |2: intros (x y z); apply Or_symmetric; apply cTf; assumption;]
113 definition reverse_pordered_set: pordered_set → pordered_set.
114 intros (p); apply (mk_pordered_set (reverse_excedence p));
115 generalize in match (reverse_excedence p); intros (E);
116 apply mk_is_porder_relation;
117 [apply le_reflexive|apply le_transitive|apply le_antisymmetric]
120 lemma is_lower_bound_reverse_is_upper_bound:
121 ∀O:pordered_set.∀a:sequence O.∀l:O.
122 is_lower_bound O a l → is_upper_bound (reverse_pordered_set O) a l.
123 intros (O a l H); unfold; intros (n); unfold reverse_pordered_set;
124 unfold reverse_excedence; simplify; fold unfold le (le ? l (a n)); apply H;
127 lemma is_upper_bound_reverse_is_lower_bound:
128 ∀O:pordered_set.∀a:sequence O.∀l:O.
129 is_upper_bound O a l → is_lower_bound (reverse_pordered_set O) a l.
130 intros (O a l H); unfold; intros (n); unfold reverse_pordered_set;
131 unfold reverse_excedence; simplify; fold unfold le (le ? (a n) l); apply H;
134 lemma reverse_is_lower_bound_is_upper_bound:
135 ∀O:pordered_set.∀a:sequence O.∀l:O.
136 is_lower_bound (reverse_pordered_set O) a l → is_upper_bound O a l.
137 intros (O a l H); unfold; intros (n); unfold reverse_pordered_set in H;
138 unfold reverse_excedence in H; simplify in H; apply H;
141 lemma reverse_is_upper_bound_is_lower_bound:
142 ∀O:pordered_set.∀a:sequence O.∀l:O.
143 is_upper_bound (reverse_pordered_set O) a l → is_lower_bound O a l.
144 intros (O a l H); unfold; intros (n); unfold reverse_pordered_set in H;
145 unfold reverse_excedence in H; simplify in H; apply H;
148 lemma is_inf_to_reverse_is_sup:
149 ∀O:pordered_set.∀a:bounded_below_sequence O.∀l:O.
150 is_inf O a l → is_sup (reverse_pordered_set O) a l.
151 intros (O a l H); apply (mk_is_sup (reverse_pordered_set O));
152 [1: apply is_lower_bound_reverse_is_upper_bound; apply inf_lower_bound; assumption
153 |2: unfold reverse_pordered_set; simplify; unfold reverse_excedence; simplify;
154 intros (m H1); apply (inf_greatest_lower_bound ? ? ? H); apply H1;]
157 lemma is_sup_to_reverse_is_inf:
158 ∀O:pordered_set.∀a:bounded_above_sequence O.∀l:O.
159 is_sup O a l → is_inf (reverse_pordered_set O) a l.
160 intros (O a l H); apply (mk_is_inf (reverse_pordered_set O));
161 [1: apply is_upper_bound_reverse_is_lower_bound; apply sup_upper_bound; assumption
162 |2: unfold reverse_pordered_set; simplify; unfold reverse_excedence; simplify;
163 intros (m H1); apply (sup_least_upper_bound ? ? ? H); apply H1;]
166 lemma reverse_is_sup_to_is_inf:
167 ∀O:pordered_set.∀a:bounded_above_sequence O.∀l:O.
168 is_sup (reverse_pordered_set O) a l → is_inf O a l.
169 intros (O a l H); apply mk_is_inf;
170 [1: apply reverse_is_upper_bound_is_lower_bound;
171 apply (sup_upper_bound (reverse_pordered_set O)); assumption
172 |2: intros (v H1); apply (sup_least_upper_bound (reverse_pordered_set O) a l H v);
173 apply is_lower_bound_reverse_is_upper_bound; assumption;]
176 lemma reverse_is_inf_to_is_sup:
177 ∀O:pordered_set.∀a:bounded_above_sequence O.∀l:O.
178 is_inf (reverse_pordered_set O) a l → is_sup O a l.
179 intros (O a l H); apply mk_is_sup;
180 [1: apply reverse_is_lower_bound_is_upper_bound;
181 apply (inf_lower_bound (reverse_pordered_set O)); assumption
182 |2: intros (v H1); apply (inf_greatest_lower_bound (reverse_pordered_set O) a l H v);
183 apply is_upper_bound_reverse_is_lower_bound; assumption;]