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/decidable_kit/fintype/".
17 include "decidable_kit/eqtype.ma".
18 include "decidable_kit/list_aux.ma".
20 record finType : Type ≝ {
23 enum_uniq : ∀x:fsort. count fsort (cmp fsort x) enum = (S O)
26 definition segment : nat → eqType ≝
27 λn.sub_eqType nat_eqType (λx:nat_eqType.ltb x n).
29 definition is_some : ∀d:eqType. option d → bool ≝
30 λd:eqType.λo:option d.notb (cmp (option_eqType d) (None ?) o).
33 λA,B:Type.λp:A→option B.λl:list A.
35 (λx,acc. match (p x) with [None ⇒ acc | (Some y) ⇒ cons B y acc]) (nil B) l.
37 definition segment_enum ≝
38 λbound.filter ? ? (if_p nat_eqType (λx.ltb x bound)) (iota O bound).
40 lemma iota_ltb : ∀x,p:nat. mem nat_eqType x (iota O p) = ltb x p.
41 intros (x p); elim p; simplify; [1:reflexivity]
43 generalize in match (refl_eq ? (cmp ? x n));
44 generalize in match (cmp ? x n) in ⊢ (? ? % ? → %); intros 1 (b);
45 cases b; simplify; intros (H1); [1: reflexivity]
46 rewrite > H; fold simplify (ltb x n); rewrite > H1; reflexivity;
50 ∀d1,d2:eqType.(*∀y:d1.*)∀x:d2.∀l:list d1.∀p:d1 → option d2.
51 (∀y.mem d1 y l = true →
52 match (p y) with [None ⇒ false | (Some q) ⇒ cmp d2 x q] = false) →
53 mem d2 x (filter d1 d2 p l) = false.
54 intros 5 (d1 d2 x l p);
55 elim l; [1: simplify; auto]
56 simplify; fold simplify (filter d1 d2 p l1);
57 generalize in match (refl_eq ? (p t));
58 generalize in match (p t) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
59 [1: simplify; intros (Hpt); apply H; intros (y Hyl);
60 apply H1; simplify; fold simplify (orb (cmp ? y t) (mem ? y l1));
61 rewrite > Hyl; rewrite > orbC; reflexivity;
62 |2:simplify; intros (Hpt);
63 generalize in match (refl_eq ? (cmp ? x s));
64 generalize in match (cmp ? x s) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
65 [1: simplify; intros (Exs);
66 rewrite < (H1 t); [2: simplify; rewrite > cmp_refl; reflexivity;]
67 rewrite > Hpt; simplify; symmetry; assumption;
68 |2: intros (Dxs); simplify; apply H; intros;
69 apply H1; simplify; fold simplify (orb (cmp ? y t) (mem ? y l1));
70 rewrite > H2; rewrite > orbC; reflexivity;]]
74 ∀d:eqType.∀p:d→bool.∀l:list d.
75 (∀x:d.mem d x l = true → notb (p x) = true) → count d p l = O.
76 intros 3 (d p l); elim l; simplify; [1: reflexivity]
77 fold simplify (count d p l1); (* XXX simplify troppo *)
78 generalize in match (refl_eq ? (p t));
79 generalize in match (p t) in ⊢ (? ? ? % → %); intros 1 (b);
81 [2:intros (Hpt); apply H; intros; apply H1; simplify;
82 generalize in match (refl_eq ? (cmp d x t));
83 generalize in match (cmp d x t) in ⊢ (? ? ? % → %); intros 1 (b1);
84 cases b1; simplify; intros; [2:rewrite > H2] auto.
85 |1:intros (H2); lapply (H1 t); [2:simplify; rewrite > cmp_refl; simplify; auto]
86 rewrite > H2 in Hletin; simplify in Hletin; destruct Hletin]
89 lemma segment_finType : nat → finType.
91 letin fsort ≝ (segment bound);
92 letin enum ≝ (segment_enum bound);
93 cut (∀x:fsort. count fsort (cmp fsort x) enum = (S O));
94 [ apply (mk_finType fsort enum Hcut)
95 | intros (x); cases x (n Hn); simplify in Hn; clear x;
96 generalize in match Hn; generalize in match Hn; clear Hn;
98 generalize in match bound in ⊢ (% → ? → ? ? (? ? ? (? ? ? ? %)) ?);
99 intros 1 (m); elim m (Hm Hn p IH Hm Hn);
101 | simplify; cases (eqP bool_eqType (ltb p bound) true); simplify;
102 (* XXX simplify che spacca troppo *)
103 fold simplify (filter nat_eqType (sigma nat_eqType (λx.ltb x bound))
104 (if_p nat_eqType (λx.ltb x bound)) (iota O p));
105 [1:unfold segment in ⊢ (? ? match ? % ? ? with [true⇒ ?|false⇒ ?] ?);
106 unfold nat_eqType in ⊢ (? ? match % with [true⇒ ?|false⇒ ?] ?);
107 simplify in ⊢ (? ? match % with [true⇒ ?|false⇒ ?] ?);
108 generalize in match (refl_eq ? (eqb n p));
109 generalize in match (eqb n p) in ⊢ (? ? ? % → %); intros 1(b);
111 [2:intros (Enp); rewrite > IH; [1,3: auto]
112 rewrite < ltb_n_Sm in Hm; rewrite > Enp in Hm;
113 generalize in match Hm; cases (ltb n p); intros; [1:reflexivity]
114 simplify in H1; destruct H1;
115 |1:clear IH; intros (Enp);
116 fold simplify (count fsort (cmp fsort {n, Hn})
117 (filter ? (sigma nat_eqType (λx.ltb x bound))
118 (if_p nat_eqType (λx.ltb x bound)) (iota O p)));
119 rewrite > (count_O fsort); [1: reflexivity]
121 rewrite < (b2pT ? ? (eqP ? n ?) Enp);
122 cases x (y Hy); intros (ABS); clear x;
123 unfold segment; unfold notb; simplify;
124 generalize in match (refl_eq ? (cmp ? n y));
125 generalize in match (cmp ? n y) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
126 intros (Eny); simplify; [2: auto]
127 rewrite < ABS; symmetry; clear ABS;
128 generalize in match Hy; clear Hy; rewrite < (b2pT ? ? (eqP nat_eqType ? ?) Eny);
129 simplify; intros (Hn); fold simplify (iota O n);
130 apply (mem_filter nat_eqType fsort);
132 fold simplify (sort nat_eqType);
133 cases (in_sub_eq nat_eqType (λx:nat_eqType.ltb x bound) w);
134 simplify; [2: reflexivity]
135 generalize in match H1; clear H1; cases s; clear s; intros (H1);
136 unfold segment; simplify; simplify in H1; rewrite > H1;
137 rewrite > iota_ltb in Hw;
138 apply (p2bF ? ? (eqP nat_eqType ? ?));
139 unfold Not; intros (Enw);
140 rewrite > Enw in Hw; rewrite > ltb_refl in Hw; destruct Hw]
141 |2:rewrite > IH; [1:reflexivity|3:assumption]
142 rewrite < ltb_n_Sm in Hm;
143 cases (b2pT ? ?(orbP ? ?) Hm);[1: assumption]
144 rewrite > (b2pT ? ? (eqbP ? ?) H1) in Hn;
145 rewrite > Hn in H; cases (H ?); reflexivity;
149 let rec uniq (d:eqType) (l:list d) on l : bool ≝
152 | (cons x tl) ⇒ andb (notb (mem d x tl)) (uniq d tl)].
154 lemma uniq_tail_OLD : ∀d:eqType.∀x:d.∀l:list d.uniq d (x::l) = true → uniq d l = true.
155 intros (d x l Uxl); simplify in Uxl; cases (b2pT ? ? (andbP ? ?) Uxl); assumption;
158 lemma uniq_mem : ∀d:eqType.∀x:d.∀l:list d.uniq d (x::l) = true → mem d x l = false.
159 intros (d x l H); simplify in H; lapply (b2pT ? ? (andbP ? ?) H) as H1; clear H;
160 cases H1 (H2 H3); lapply (b2pT ? ?(negbP ?) H2); assumption;
163 lemma andbA : ∀a,b,c.andb a (andb b c) = andb (andb a b) c.
164 intros; cases a; cases b; cases c; reflexivity; qed.
166 lemma andbC : ∀a,b. andb a b = andb b a.
167 intros; cases a; cases b; reflexivity; qed.
170 ∀d:eqType.∀x:d.∀l:list d. uniq d (x::l) = andb (negb (mem d x l)) (uniq d l).
172 elim l; [1: simplify; reflexivity]
173 generalize in match (refl_eq ? (cmp d x t));
174 generalize in match (cmp d x t) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
175 intros (E); simplify ; rewrite > E; simplify; [1: reflexivity;]
176 rewrite > andbA; rewrite > andbC in ⊢ (? ? (? % ?) ?); rewrite < andbA;
177 rewrite < H; rewrite > andbC in ⊢ (? ? ? (? % ?)); rewrite < andbA;
181 lemma count_O_mem : ∀d:eqType.∀x:d.∀l:list d.ltb O (count d (cmp d x) l) = mem d x l.
182 intros 3 (d x l); elim l [reflexivity]
183 simplify; fold simplify (mem d x l1); fold simplify (count d (cmp d x) l1);
184 rewrite < H; cases (cmp d x t); simplify; reflexivity;
187 lemma uniqP : ∀d:eqType.∀l:list d.
188 reflect (∀x:d.mem d x l = true → count d (cmp d x) l = (S O)) (uniq d l).
189 intros (d l); apply prove_reflect; elim l; [1: destruct H1 | 3: destruct H]
190 [1: generalize in match H2; simplify in H2; fold simplify (orb (cmp d x t) (mem d x l1)) in H2;
191 (* lapply (uniq_tail ? ? ? H1) as Ul1; *)
192 lapply (b2pT ? ? (orbP ? ?) H2) as H3; clear H2;
193 cases H3; clear H3; intros;
194 [2: lapply (uniq_mem ? ? ? H1) as H4;
195 generalize in match (refl_eq ? (cmp d x t));
196 generalize in match (cmp d x t) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
198 [1: simplify; rewrite > H5; simplify; fold simplify (count d (cmp d x) l1);
199 rewrite > count_O; [1:reflexivity]
200 intros (y Hy); rewrite > (b2pT ? ? (eqP d ? ?) H5) in H2 H3 H4 ⊢ %;
201 clear H5; clear x; rewrite > H2 in H4; destruct H4;
202 |2: simplify; rewrite > H5; simplify;
203 fold simplify (count d (cmp d x) (l1));
204 apply H; rewrite > uniq_tail in H1;
205 cases (b2pT ? ? (andbP ? ?) H1);
207 |1: simplify; rewrite > H2; simplify;
208 fold simplify (count d (cmp d x) l1);
209 rewrite > count_O; [1:reflexivity]
210 intros (y Hy); rewrite > (b2pT ? ? (eqP d ? ?) H2) in H3 ⊢ %;
212 lapply (uniq_mem ? ? ? H1) as H4;
213 generalize in match (refl_eq ? (cmp d t y));
214 generalize in match (cmp d t y) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
215 [1: intros (E); rewrite > (b2pT ? ? (eqP d ? ?) E) in H4;
216 rewrite > H4 in Hy; destruct Hy;
217 |2:intros; reflexivity]]
218 |2: rewrite > uniq_tail in H1;
219 generalize in match (refl_eq ? (uniq d l1));
220 generalize in match (uniq d l1) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
221 [1: intros (E); rewrite > E in H1; rewrite > andbC in H1; simplify in H1;
222 unfold Not; intros (A); lapply (A t) as A';
224 rewrite > cmp_refl in A'; simplify in A';
225 destruct A'; clear A'; fold simplify (count d (cmp d t) l1) in Hcut;
226 rewrite < count_O_mem in H1;
227 rewrite > Hcut in H1; destruct H1;
228 |2: simplify; rewrite > cmp_refl; reflexivity;]
229 |2: intros (Ul1); lapply (H Ul1); unfold Not; intros (A); apply Hletin;
230 intros (r Mrl1); lapply (A r); [2: simplify; rewrite > Mrl1; cases (cmp d r t); reflexivity]
231 generalize in match (refl_eq ? (cmp d r t));
232 generalize in match (cmp d r t) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
233 [1: intros (E); simplify in Hletin1; rewrite > E in Hletin1;
234 simplify in Hletin1; fold simplify (count d (cmp d r) l1) in Hletin1;
236 rewrite < count_O_mem in Mrl1;
237 rewrite > Hcut in Mrl1;
239 |2: intros; simplify in Hletin1; rewrite > H2 in Hletin1;
240 simplify in Hletin1; apply (Hletin1);]]]
243 lemma mem_finType : ∀d:finType.∀x:d. mem d x (enum d) = true.
244 intros 1 (d); cases d; simplify; intros; rewrite < count_O_mem;
245 rewrite > H; reflexivity;
248 lemma uniq_fintype_enum : ∀d:finType. uniq d (enum d) = true.
249 intros; cases d; simplify; apply (p2bT ? ? (uniqP ? ?)); intros; apply H;
252 lemma sub_enumP : ∀d:finType.∀p:d→bool.∀x:sub_eqType d p.
253 count (sub_eqType d p) (cmp ? x) (filter ? ? (if_p ? p) (enum d)) = (S O).
254 intros (d p x); cases x (t Ht); clear x;
255 generalize in match (mem_finType d t);
256 generalize in match (uniq_fintype_enum d);
257 elim (enum d); [1:destruct H1]
258 simplify; fold simplify (filter d (sigma d p) (if_p d p) l);
259 cases (in_sub_eq d p t1); simplify in ⊢ (? ? (? ? ? %) ?);
260 [simplify; fold simplify (count (sub_eqType d p) (cmp (sub_eqType d p) {t,Ht})
261 (filter d (sigma d p) (if_p d p) l));
262 generalize in match H3; clear H3; cases s (r Hr); clear s;
263 simplify; intros (Ert1); generalize in match Hr; clear Hr;
264 rewrite > Ert1; clear Ert1; clear r; intros (Ht1);
265 unfold sub_eqType in ⊢ (? ? match ? (% ? ?) ? ? with [true⇒ ?|false⇒ ?] ?);
266 simplify; generalize in match (refl_eq ? (cmp d t t1));
267 generalize in match (cmp d t t1) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
268 intros (Ett1); simplify;
269 [1: cut (count (sub_eqType d p) (cmp (sub_eqType d p) {t,Ht})
270 (filter d (sigma d p) (if_p d p) l) = O); [1:rewrite > Hcut; reflexivity]
271 lapply (uniq_mem ? ? ? H1);
272 generalize in match Ht;
273 rewrite > (b2pT ? ? (eqP d ? ?) Ett1); intros (Ht1'); clear Ht1;
274 generalize in match Hletin; elim l; [1: reflexivity]
275 simplify; cases (in_sub_eq d p t2); simplify;
276 [1: generalize in match H5; cases s; simplify; intros; clear H5;
277 unfold sub_eqType in ⊢ (? ? match ? (% ? ?) ? ? with [true⇒ ?|false⇒ ?] ?);
278 simplify; rewrite > H7; simplify in H4;
279 generalize in match H4; clear H4;
280 generalize in match (refl_eq ? (cmp d t1 t2));
281 generalize in match (cmp d t1 t2) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
282 simplify; intros; [1: destruct H5] apply H3; assumption
284 generalize in match H4; clear H4; simplify;
285 generalize in match (refl_eq ? (cmp d t1 t2));
286 generalize in match (cmp d t1 t2) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
287 simplify; intros; [1: destruct H6] assumption;]
288 |2: apply H; [ rewrite > uniq_tail in H1; cases (b2pT ? ? (andbP ? ?) H1); assumption]
289 simplify in H2; rewrite > Ett1 in H2; simplify in H2; assumption]
290 | rewrite > H; [1:reflexivity|2: rewrite > uniq_tail in H1; cases (b2pT ? ? (andbP ? ?) H1); assumption]
291 simplify in H2; generalize in match H2; generalize in match (refl_eq ? (cmp d t t1));
292 generalize in match (cmp d t t1) in ⊢ (? ? ? % → %); intros 1 (b); cases b; clear b;
294 [lapply (b2pT ? ? (eqP d ? ?) E); clear H; rewrite > Hletin in Ht;
295 rewrite > Ht in H3; destruct H3;
299 definition sub_finType : ∀d:finType.∀p:d→bool.finType ≝
300 λd:finType.λp:d→bool. mk_finType (sub_eqType d p) (filter ? ? (if_p ? p) (enum d)) (sub_enumP d p).