The real numbers are an Archimedean floor ring, and a conditionally complete linear order. #
Equations
- Real.instArchimedean = (_ : Archimedean ℝ)
Equations
- Real.instSupSetReal = { sSup := fun (S : Set ℝ) => if h : Set.Nonempty S ∧ BddAbove S then Classical.choose (_ : ∃ (x : ℝ), IsLUB S x) else 0 }
theorem
Real.sSup_def
(S : Set ℝ)
:
sSup S = if h : Set.Nonempty S ∧ BddAbove S then Classical.choose (_ : ∃ (x : ℝ), IsLUB S x) else 0
Equations
- One or more equations did not get rendered due to their size.
As 0
is the default value for Real.sSup
of the empty set or sets which are not bounded above, it
suffices to show that all elements of S
are bounded by a nonnegative number to show that sSup S
is bounded by this number.