Module MyNat.
End MyNat.
Open Scope R_scope.
(** * Integers *)
(** Integer part in Z *)
Definition floor x := proj1_sig (floor_ex x).
Definition floor1 x := proj1_sig (floor1_ex x).
(** Interger part in nat *)
Definition nfloor x pr := proj1_sig (nfloor_ex x pr).
Definition nfloor1 x pr := proj1_sig (nfloor1_ex x pr).
(** More theorems about INR *)
Fixpoint pow2 (n : nat) : nat :=
match n with
| O => 1%nat
| S n => (2 * pow2 n)%nat
end.
(** * Rinv *)
(** * Rdiv *)
(** Rewritings *)
(** Order *)
(** * Rmult *)
(** * Rminus *)
(** Rewritings *)
(** Order *)
(** * Rplus *)
(** Sums *)

Lemma sum_f_chasles (u : nat -> R) (n m k : nat) :
(n < m)%nat -> (m < k)%nat ->
sum_f (S n) k u = sum_f (S n) m u + sum_f (S m) k u.