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(** *    Injection from N to R                            *)
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Fixpoint INR (n:nat) : R :=
match n with
| O => 0
| S O => 1
| S n => INR n + 1
end.
Arguments INR n%_nat.
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(** *    [R] Archimedean                                  *)
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Lemma archimed : forall r:R, IZR (up r) > r /\ IZR (up r) - r <= 1.
Definition is_upper_bound (E:R -> Prop) (m:R) := forall x:R, E x -> x <= m.