include "nat/primes.ma".
include "nat/ord.ma".
include "nat/generic_sigma_p.ma".
+include "nat/count.ma".(*necessary just to use bool_to_nat and bool_to_nat_andb*)
(* sigma_p on nautral numbers is a specialization of sigma_p_gen *)
]
qed.
+(*some properties of sigma_p invoked with an "always true" predicate (in this
+ way sigma_p just counts the elements, without doing any control) or with
+ the nat \to nat function which always returns (S O).
+ It 's not easily possible proving these theorems in a general form
+ in generic_sigma_p.ma
+ *)
+
+theorem sigma_p_true: \forall n:nat.
+(sigma_p n (\lambda x.true) (\lambda x.S O)) = n.
+intros.
+elim n
+[ simplify.
+ reflexivity
+| rewrite > (true_to_sigma_p_Sn n1 (\lambda x:nat.true) (\lambda x:nat.S O))
+ [ rewrite > H.
+ simplify.
+ reflexivity
+ | reflexivity
+ ]
+]
+qed.
+
+theorem sigma_P_SO_to_sigma_p_true: \forall n:nat. \forall g:nat \to bool.
+sigma_p n g (\lambda n:nat. (S O)) =
+sigma_p n (\lambda x:nat.true) (\lambda i:nat.bool_to_nat (g i)).
+intros.
+elim n
+[ simplify.
+ reflexivity
+| cut ((g n1) = true \lor (g n1) = false)
+ [ rewrite > true_to_sigma_p_Sn in \vdash (? ? ? %)
+ [ elim Hcut
+ [ rewrite > H1.
+ rewrite > true_to_sigma_p_Sn in \vdash (? ? % ?)
+ [ simplify.
+ apply eq_f.
+ assumption
+ | assumption
+ ]
+ | rewrite > H1.
+ rewrite > false_to_sigma_p_Sn in \vdash (? ? % ?)
+ [ simplify.
+ assumption
+ | assumption
+ ]
+ ]
+ | reflexivity
+ ]
+ | elim (g n1)
+ [ left.
+ reflexivity
+ | right.
+ reflexivity
+ ]
+ ]
+]
+qed.
+
+(* I introduce an equivalence in the form map_iter_i in order to use
+ * the existing result about permutation in that part of the library.
+ *)
+
+theorem eq_map_iter_i_sigma_p_alwaysTrue: \forall n:nat.\forall g:nat \to nat.
+map_iter_i n g plus O = sigma_p (S n) (\lambda c:nat.true) g.
+intros.
+elim n
+[ simplify.
+ rewrite < plus_n_O.
+ reflexivity
+| rewrite > true_to_sigma_p_Sn
+ [ simplify in \vdash (? ? % ?).
+ rewrite < plus_n_O.
+ apply eq_f.
+ assumption
+ | reflexivity
+ ]
+]
+qed.
+
+theorem sigma_p_plus_1: \forall n:nat. \forall f,g:nat \to nat.
+sigma_p n (\lambda b:nat. true) (\lambda a:nat.(f a) + (g a)) =
+sigma_p n (\lambda b:nat. true) f + sigma_p n (\lambda b:nat. true) g.
+intros.
+elim n
+[ simplify.
+ reflexivity
+| rewrite > true_to_sigma_p_Sn
+ [ rewrite > (true_to_sigma_p_Sn n1 (\lambda c:nat.true) f)
+ [ rewrite > (true_to_sigma_p_Sn n1 (\lambda c:nat.true) g)
+ [ rewrite > assoc_plus in \vdash (? ? ? %).
+ rewrite < assoc_plus in \vdash (? ? ? (? ? %)).
+ rewrite < sym_plus in \vdash (? ? ? (? ? (? % ?))).
+ rewrite > assoc_plus in \vdash (? ? ? (? ? %)).
+ rewrite < assoc_plus in \vdash (? ? ? %).
+ apply eq_f.
+ assumption
+ | reflexivity
+ ]
+ | reflexivity
+ ]
+ | reflexivity
+ ]
+]
+qed.
+
+
+theorem eq_sigma_p_sigma_p_times1 : \forall n,m:nat.\forall f:nat \to nat.
+sigma_p (n*m) (\lambda x:nat.true) f =
+sigma_p m (\lambda x:nat.true)
+ (\lambda a.(sigma_p n (\lambda x:nat.true) (\lambda b.f (b*m + a)))).
+intro.
+elim n
+[ simplify.
+ elim m
+ [ simplify.
+ reflexivity
+ | rewrite > true_to_sigma_p_Sn
+ [ rewrite < H.
+ reflexivity
+ | reflexivity
+ ]
+ ]
+| change in \vdash (? ? ? (? ? ? (\lambda a:?.%))) with ((f ((n1*m)+a)) +
+ (sigma_p n1 (\lambda x:nat.true) (\lambda b:nat.f (b*m +a)))).
+ rewrite > sigma_p_plus_1 in \vdash (? ? ? %).
+ rewrite > (sym_times (S n1) m).
+ rewrite < (times_n_Sm m n1).
+ rewrite > sigma_p_plus in \vdash (? ? % ?).
+ apply eq_f2
+ [ rewrite < (sym_times m n1).
+ apply eq_sigma_p
+ [ intros.
+ reflexivity
+ | intros.
+ rewrite < (sym_plus ? (m * n1)).
+ reflexivity
+ ]
+ | rewrite > (sym_times m n1).
+ apply H
+ ]
+]
+qed.
+
+theorem eq_sigma_p_sigma_p_times2 : \forall n,m:nat.\forall f:nat \to nat.
+sigma_p (n *m) (\lambda c:nat.true) f =
+sigma_p n (\lambda c:nat.true)
+ (\lambda a.(sigma_p m (\lambda c:nat.true) (\lambda b:nat.f (b* n + a)))).
+intros.
+rewrite > sym_times.
+apply eq_sigma_p_sigma_p_times1.
+qed.
+
+
+theorem sigma_p_times:\forall n,m:nat.
+\forall f,f1,f2:nat \to bool.
+\forall g:nat \to nat \to nat.
+\forall g1,g2: nat \to nat.
+(\forall a,b:nat. a < (S n) \to b < (S m) \to (g b a) < (S n)*(S m)) \to
+(\forall a,b:nat. a < (S n) \to b < (S m) \to (g1 (g b a)) = a) \to
+(\forall a,b:nat. a < (S n) \to b < (S m) \to (g2 (g b a)) = b) \to
+(\forall a,b:nat. a < (S n) \to b < (S m) \to f (g b a) = andb (f2 b) (f1 a)) \to
+(sigma_p ((S n) * (S m)) f (\lambda c:nat.(S O))) =
+sigma_p (S n) f1 (\lambda c:nat.(S O)) * sigma_p (S m) f2 (\lambda c:nat.(S O)).
+intros.
+
+rewrite > (sigma_P_SO_to_sigma_p_true ).
+rewrite > (S_pred ((S n)*(S m))) in \vdash (? ? (? % ? ?) ?)
+[ rewrite < (eq_map_iter_i_sigma_p_alwaysTrue (pred ((S n)* (S m)))).
+ rewrite > (permut_to_eq_map_iter_i plus assoc_plus sym_plus ? ? ?
+ (\lambda i.g (div i (S n)) (mod i (S n))))
+ [ rewrite > eq_map_iter_i_sigma_p_alwaysTrue.
+ rewrite < S_pred
+ [ rewrite > eq_sigma_p_sigma_p_times2.
+ apply (trans_eq ? ? (sigma_p (S n) (\lambda c:nat.true)
+ (\lambda a. sigma_p (S m) (\lambda c:nat.true)
+ (\lambda b.(bool_to_nat (f2 b))*(bool_to_nat (f1 a))))))
+ [ apply eq_sigma_p;intros
+ [ reflexivity
+ | apply eq_sigma_p;intros
+ [ reflexivity
+ |
+ rewrite > (div_mod_spec_to_eq (x1*(S n) + x) (S n) ((x1*(S n) + x)/(S n))
+ ((x1*(S n) + x) \mod (S n)) x1 x)
+ [ rewrite > (div_mod_spec_to_eq2 (x1*(S n) + x) (S n) ((x1*(S n) + x)/(S n))
+ ((x1*(S n) + x) \mod (S n)) x1 x)
+ [ rewrite > H3
+ [ apply bool_to_nat_andb
+ | assumption
+ | assumption
+ ]
+ | apply div_mod_spec_div_mod.
+ apply lt_O_S
+ | constructor 1
+ [ assumption
+ | reflexivity
+ ]
+ ]
+ | apply div_mod_spec_div_mod.
+ apply lt_O_S
+ | constructor 1
+ [ assumption
+ | reflexivity
+ ]
+ ]
+ ]
+ ]
+ | apply (trans_eq ? ?
+ (sigma_p (S n) (\lambda c:nat.true) (\lambda n.((bool_to_nat (f1 n)) *
+ (sigma_p (S m) (\lambda c:nat.true) (\lambda n.bool_to_nat (f2 n)))))))
+ [ apply eq_sigma_p;intros
+ [ reflexivity
+ | rewrite > distributive_times_plus_sigma_p.
+ apply eq_sigma_p;intros
+ [ reflexivity
+ | rewrite > sym_times.
+ reflexivity
+ ]
+ ]
+ | apply sym_eq.
+ rewrite > sigma_P_SO_to_sigma_p_true.
+ rewrite > sigma_P_SO_to_sigma_p_true in \vdash (? ? (? ? %) ?).
+ rewrite > sym_times.
+ rewrite > distributive_times_plus_sigma_p.
+ apply eq_sigma_p;intros
+ [ reflexivity
+ | rewrite > distributive_times_plus_sigma_p.
+ rewrite < sym_times.
+ rewrite > distributive_times_plus_sigma_p.
+ apply eq_sigma_p;
+ intros; reflexivity
+ ]
+ ]
+ ]
+ | apply lt_O_times_S_S
+ ]
+
+ | unfold permut.
+ split
+ [ intros.
+ rewrite < plus_n_O.
+ apply le_S_S_to_le.
+ rewrite < S_pred in \vdash (? ? %)
+ [ change with ((g (i/(S n)) (i \mod (S n))) \lt (S n)*(S m)).
+ apply H
+ [ apply lt_mod_m_m.
+ unfold lt.
+ apply le_S_S.
+ apply le_O_n
+ | apply (lt_times_to_lt_l n).
+ apply (le_to_lt_to_lt ? i)
+ [ rewrite > (div_mod i (S n)) in \vdash (? ? %)
+ [ rewrite > sym_plus.
+ apply le_plus_n
+ | unfold lt.
+ apply le_S_S.
+ apply le_O_n
+ ]
+ | unfold lt.
+ rewrite > S_pred in \vdash (? ? %)
+ [ apply le_S_S.
+ rewrite > plus_n_O in \vdash (? ? %).
+ rewrite > sym_times.
+ assumption
+ | apply lt_O_times_S_S
+ ]
+ ]
+ ]
+ | apply lt_O_times_S_S
+ ]
+ | rewrite < plus_n_O.
+ unfold injn.
+ intros.
+ cut (i < (S n)*(S m))
+ [ cut (j < (S n)*(S m))
+ [ cut ((i \mod (S n)) < (S n))
+ [ cut ((i/(S n)) < (S m))
+ [ cut ((j \mod (S n)) < (S n))
+ [ cut ((j/(S n)) < (S m))
+ [ rewrite > (div_mod i (S n))
+ [ rewrite > (div_mod j (S n))
+ [ rewrite < (H1 (i \mod (S n)) (i/(S n)) Hcut2 Hcut3).
+ rewrite < (H2 (i \mod (S n)) (i/(S n)) Hcut2 Hcut3) in \vdash (? ? (? % ?) ?).
+ rewrite < (H1 (j \mod (S n)) (j/(S n)) Hcut4 Hcut5).
+ rewrite < (H2 (j \mod (S n)) (j/(S n)) Hcut4 Hcut5) in \vdash (? ? ? (? % ?)).
+ rewrite > H6.
+ reflexivity
+ | unfold lt.
+ apply le_S_S.
+ apply le_O_n
+ ]
+ | unfold lt.
+ apply le_S_S.
+ apply le_O_n
+ ]
+ | apply (lt_times_to_lt_l n).
+ apply (le_to_lt_to_lt ? j)
+ [ rewrite > (div_mod j (S n)) in \vdash (? ? %)
+ [ rewrite > sym_plus.
+ apply le_plus_n
+ | unfold lt. apply le_S_S.
+ apply le_O_n
+ ]
+ | rewrite < sym_times.
+ assumption
+ ]
+ ]
+ | apply lt_mod_m_m.
+ unfold lt.
+ apply le_S_S.
+ apply le_O_n
+ ]
+ | apply (lt_times_to_lt_l n).
+ apply (le_to_lt_to_lt ? i)
+ [ rewrite > (div_mod i (S n)) in \vdash (? ? %)
+ [ rewrite > sym_plus.
+ apply le_plus_n
+ | unfold lt.
+ apply le_S_S.
+ apply le_O_n
+ ]
+ | rewrite < sym_times.
+ assumption
+ ]
+ ]
+ | apply lt_mod_m_m.
+ unfold lt.
+ apply le_S_S.
+ apply le_O_n
+ ]
+ | unfold lt.
+ rewrite > S_pred in \vdash (? ? %)
+ [ apply le_S_S.
+ assumption
+ | apply lt_O_times_S_S
+ ]
+ ]
+ | unfold lt.
+ rewrite > S_pred in \vdash (? ? %)
+ [ apply le_S_S.
+ assumption
+ | apply lt_O_times_S_S
+ ]
+ ]
+ ]
+ | intros.
+ apply False_ind.
+ apply (not_le_Sn_O m1 H4)
+ ]
+| apply lt_O_times_S_S
+]
+qed.
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