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 include "sets/sets.ma".
16 include "nat/plus.ma".
17 include "nat/compare.ma".
18 include "nat/minus.ma".
20 alias symbol "eq" = "setoid eq".
21 alias symbol "eq" = "setoid1 eq".
22 alias symbol "eq" = "setoid eq".
23 alias symbol "eq" = "setoid1 eq".
24 alias symbol "eq" = "setoid eq".
25 alias symbol "eq" = "setoid1 eq".
26 alias symbol "eq" = "setoid eq".
27 alias symbol "eq" = "setoid1 eq".
28 nrecord partition (A: setoid) : Type[1] ≝
30 indexes: qpowerclass support;
31 class: unary_morphism1 (setoid1_of_setoid support) (qpowerclass_setoid A);
32 inhabited: ∀i. i ∈ indexes → class i ≬ class i;
33 disjoint: ∀i,j. i ∈ indexes → j ∈ indexes → class i ≬ class j → i=j;
34 covers: big_union support ? ? (λx.class x) = full_set A
35 }. napply indexes; nqed.
39 nlet rec partition_splits_card_map
40 A (P:partition A) n s (f:isomorphism ?? (Nat_ n) (indexes ? P))
41 (fi: ∀i. isomorphism ?? (Nat_ (s i)) (class ? P (iso_f ???? f i))) m index
43 match ltb m (s index) with
44 [ true ⇒ iso_f ???? (fi index) m
47 [ O ⇒ (* dummy value: it could be an elim False: *) iso_f ???? (fi O) O
49 partition_splits_card_map A P n s f fi (minus m (s index)) index']].
51 naxiom big_union_preserves_iso:
53 ∀g: isomorphism A' A T' T.
54 big_union A B T f = big_union A' B T' (λx.f (iso_f ???? g x)).
56 naxiom le_to_lt_or_eq: ∀n,m. n ≤ m → n < m ∨ n = m.
57 alias symbol "eq" = "leibnitz's equality".
58 naxiom minus_canc: ∀n. O = minus n n.
59 naxiom lt_to_ltb_t: ∀n,m. ∀P: bool → CProp[0]. P true → n < m → P (ltb n m).
60 naxiom lt_to_ltb_f: ∀n,m. ∀P: bool → CProp[0]. P false → ¬ (n < m) → P (ltb n m).
61 naxiom lt_to_minus: ∀n,m. n < m → S (minus (minus m n) (S O)) = minus m n.
62 naxiom not_lt_O: ∀n. ¬ (n < O).
63 naxiom minus_S: ∀n,m. m ≤ n → minus (S n) m = S (minus n m).
64 naxiom minus_lt_to_lt: ∀n,m,p. n < p → minus n m < p.
65 naxiom minus_O_n: ∀n. O = minus O n.
66 naxiom le_O_to_eq: ∀n. n ≤ O → n=O.
67 naxiom lt_to_minus_to_S: ∀n,m. m < n → ∃k. minus n m = S k.
68 naxiom ltb_t: ∀n,m. n < m → ltb n m = true.
70 nlemma partition_splits_card:
71 ∀A. ∀P:partition A. ∀n,s.
72 ∀f:isomorphism ?? (Nat_ n) (indexes ? P).
73 (∀i. isomorphism ?? (Nat_ (s i)) (class ? P (iso_f ???? f i))) →
74 (isomorphism ?? (Nat_ (big_plus n (λi.λ_.s i))) (Full_set A)).
75 #A; #P; #Sn; ncases Sn
77 ngeneralize in match (covers ? P) in ⊢ ?; *; #_; #H;
79 (big_union_preserves_iso ??? (indexes A P) (Nat_ O) (λx.class ? P x) f) in ⊢ ?;
80 *; #K; #_; nwhd in K: (? → ? → %);
81 nelim daemon (* impossibile *)
82 | #n; #s; #f; #fi; napply mk_isomorphism
83 [ napply mk_unary_morphism
84 [ napply (λm.partition_splits_card_map A P (S n) s f fi m n)
85 | #a; #a'; #H; nrewrite < H; napply refl ]
87 ngeneralize in match (covers ? P) in ⊢ ?; *; #_; #Hc;
88 ngeneralize in match (Hc y I) in ⊢ ?; *; #index; *; #Hi1; #Hi2;
89 ngeneralize in match (f_sur ???? f ? Hi1) in ⊢ ?; *; #nindex; *; #Hni1; #Hni2;
90 ngeneralize in match (f_sur ???? (fi nindex) y ?) in ⊢ ?
91 [##2: napply (. #‡(†?));##[##3: napply Hni2 |##2: ##skip | nassumption]##]
92 *; #nindex2; *; #Hni21; #Hni22;
93 nletin xxx ≝ (plus match minus n nindex return λ_.nat with [ O ⇒ O | S nn ⇒ big_plus nn (λi.λ_.s (S (plus i nindex)))] nindex2);
94 napply (ex_intro … xxx); napply conj
95 [ nwhd in Hni1; nwhd; nelim daemon
97 nchange in Hni1 with (nindex < S n);
98 ngeneralize in match (le_S_S_to_le … Hni1) in ⊢ ?;
99 nwhd in ⊢ (? → ???(???????%?)?);
100 napply (nat_rect_CProp0
102 partition_splits_card_map A P (S n) s f fi
104 match minus x nindex with
105 [ O ⇒ O | S nn ⇒ big_plus nn (λi.λ_.s (S (plus i nindex)))]
106 nindex2) x = y) ?? n)
107 [ #K; nrewrite < (minus_O_n nindex); nwhd in ⊢ (???(???????%?)?);
108 nwhd in ⊢ (???%?); nchange in Hni21 with (nindex2 < s nindex);
109 ngeneralize in match (le_O_to_eq … K) in ⊢ ?; #K';
110 ngeneralize in match Hni21 in ⊢ ?;
111 ngeneralize in match Hni22 in ⊢ ?;
112 nrewrite > K' in ⊢ (% → % → ?); #K1; #K2;
113 nrewrite > (ltb_t … K2);
114 nwhd in ⊢ (???%?); nassumption
115 | #n'; #Hrec; #HH; nelim (le_to_lt_or_eq … HH)
116 [##2: #K; nrewrite < K; nrewrite < (minus_canc nindex);
117 nwhd in ⊢ (???(???????%?)?);
119 ##| #K; nwhd in ⊢ (???%?);
120 nrewrite > (minus_S n' nindex ?) [##2: napply le_S_S_to_le; nassumption]
121 ngeneralize in match (? :
122 match S (minus n' nindex) with [O ⇒ O | S nn ⇒ big_plus nn (λi.λ_.s (S (plus i nindex)))]
123 = big_plus (minus n' nindex) (λi.λ_.s (S (plus i nindex)))) in ⊢ ? [##2: napply refl]
124 #He; napply (eq_rect_CProp0_r ??
126 match ltb (plus x nindex2) (s (S n')) with
127 [ true ⇒ iso_f ???? (fi (S n')) (plus x nindex2)
128 | false ⇒ ?(*partition_splits_card_map A P (S n) s f fi
129 (minus (plus x nindex2) (s (S n'))) n'*)
132 ngeneralize in match (? :
133 ltb (plus (big_plus (minus n' nindex) (λi.λ_.s (S (plus i nindex)))) nindex2)
134 (s (S n')) = false) in ⊢ ?
135 [ #Hc; nrewrite > Hc; nwhd in ⊢ (???%?);
136 nelim (le_to_lt_or_eq … (le_S_S_to_le … K))
138 ##| #E; ngeneralize in match Hc in ⊢ ?;
139 nrewrite < E; nrewrite < (minus_canc nindex);
140 nwhd in ⊢ (??(?%?)? → ?);
141 nrewrite > E in Hni21; #E'; nchange in E' with (nindex2 < s n');
142 ngeneralize in match Hni21 in ⊢ ?;
145 ngeneralize in match (? :
146 minus (plus (big_plus (minus n' nindex) (λi.λ_.s (S (plus i nindex)))) nindex2)
150 match minus n' nindex with
151 [ O ⇒ O | S nn ⇒ big_plus nn (λi.λ_.s (S (plus i nindex)))] nindex2)
153 [ #F; nrewrite > F; napply Hrec; napply le_S_S_to_le; nassumption
154 | nelim (le_to_lt_or_eq … (le_S_S_to_le … K))
156 ##| #E; nrewrite < E; nrewrite < (minus_canc nindex); nnormalize;
165 nnormalize in ⊢ (???%?);
169 nelim (le_to_lt_or_eq … K)
170 [##2: #K'; nrewrite > K'; nrewrite < (minus_canc n); nnormalize;
171 napply (eq_rect_CProp0 nat nindex (λx:nat.λ_.partition_splits_card_map A P (S n) s f fi nindex2 x = y) ? n K');
172 nchange in Hni21 with (nindex2 < s nindex); ngeneralize in match Hni21 in ⊢ ?;
173 ngeneralize in match Hni22 in ⊢ ?;
175 [ #X1; #X2; nwhd in ⊢ (??? % ?);
176 napply (lt_to_ltb_t ???? X2); #D; nwhd in ⊢ (??? % ?); nassumption
177 | #n0; #_; #X1; #X2; nwhd in ⊢ (??? % ?);
178 napply (lt_to_ltb_t ???? X2); #D; nwhd in ⊢ (??? % ?); nassumption]
179 ##| #K'; ngeneralize in match (lt_to_minus … K') in ⊢ ?; #K2;
180 napply (eq_rect_CProp0 ?? (λx.λ_.?) ? ? K2); (* uffa, ancora??? *)
181 nwhd in ⊢ (??? (???????(?%?)?) ?);
182 ngeneralize in match K' in ⊢ ?;
183 napply (nat_rect_CProp0
185 partition_splits_card_map A P (S n) s f fi
186 (plus (big_op plus_magma_type (minus (minus x nindex) (S O))
187 (λi.λ_.s (S (plus i nindex))) O) nindex2) x = y) ?? n)
188 [ #A; nelim (not_lt_O … A)
189 | #n'; #Hrec; #X; nwhd in ⊢ (???%?);
191 (? : ¬ ((plus (big_op plus_magma_type (minus (minus (S n') nindex) (S O))
192 (λi.λ_.s (S (plus i nindex))) O) nindex2) < s (S n'))) in ⊢ ?
193 [ #B1; napply (lt_to_ltb_f ???? B1); #B1'; nwhd in ⊢ (???%?);
194 nrewrite > (minus_S n' nindex …) [##2: napply le_S_S_to_le; nassumption]
195 ngeneralize in match (le_S_S_to_le … X) in ⊢ ?; #X';
196 nelim (le_to_lt_or_eq … X')
198 nchange in Hni21 with (nindex2 < s nindex); ngeneralize in match Hni21 in ⊢ ?;
199 nrewrite > X''; nrewrite < (minus_canc n');
200 nrewrite < (minus_canc (S O)); nnormalize in ⊢ (? → %);
202 [ #Y; nwhd in ⊢ (??? % ?);
203 ngeneralize in match (minus_lt_to_lt ? (s (S O)) ? Y) in ⊢ ?; #Y';
204 napply (lt_to_ltb_t … Y'); #H; nwhd in ⊢ (???%?);
206 nrewrite > (minus_S (minus n' nindex) (S O) …) [##2:
213 (* BEL POSTO DOVE FARE UN LEMMA *)
214 (* invariante: Hni1; altre premesse: Hni1, Hni22 *)
215 nelim n in ⊢ (% → ??? (????????%) ?)
217 | #index'; #Hrec; #K; nwhd in ⊢ (???%?);
218 nelim (ltb xxx (s (S index')));
219 #K1; nwhd in ⊢ (???%?)
222 nindex < S index' + 1
223 +^{nindex} (s i) w < s (S index')
230 | #x; #x'; nnormalize in ⊢ (? → ? → %);
235 (************** equivalence relations vs partitions **********************)
237 ndefinition partition_of_compatible_equivalence_relation:
238 ∀A:setoid. compatible_equivalence_relation A → partition A.
239 #A; #R; napply mk_partition
240 [ napply (quotient ? R)
242 | #a; napply mk_qpowerclass
244 | #x; #x'; #H; nnormalize; napply mk_iff; #K; nelim daemon]
245 ##| #x; #_; nnormalize; napply (ex_intro … x); napply conj; napply refl
246 | #x; #x'; #_; #_; nnormalize; *; #x''; *; #H1; #H2; napply (trans ?????? H2);
247 napply sym; nassumption
248 | nnormalize; napply conj
249 [ #a; #_; napply I | #a; #_; napply (ex_intro … a); napply conj [ napply I | napply refl]##]