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AlexKontorovich/PrimeNumberTheoremAnd
Source indexedtheorem · leanprover/lean4:v4.32.0

riemannZetaLogDerivResidue

PrimeNumberTheoremAnd.ZetaBounds · PrimeNumberTheoremAnd/ZetaBounds.lean:578 to 623

Source documentation

As a corollary, the log derivative of the Riemann zeta function has a simple pole at s=1s=1:

Exact Lean statement

@[blueprint
  (title := "riemannZetaLogDerivResidue")
  (statement := /--
  The log derivative of the Riemann zeta function $\zeta(s)$ has a simple pole at $s=1$ with
  residue $-1$: $-\frac{\zeta'(s)}{\zeta(s)} - \frac{1}{s-1} = O(1)$.
  -/)
  (proof := /--
  This follows from Theorem \ref{logDerivResidue} and Theorem \ref{riemannZetaResidue}.
  -/)]
theorem riemannZetaLogDerivResidue :
    ∃ U ∈ 𝓝 1, BddAbove (norm ∘ (-(ζ' / ζ) - (fun s ↦ (s - 1)⁻¹)) '' (U \ {1}))

Complete declaration

Lean source

Canonical source
Full Lean sourceLean 4
@[blueprint  (title := "riemannZetaLogDerivResidue")  (statement := /--  The log derivative of the Riemann zeta function $\zeta(s)$ has a simple pole at $s=1$ with  residue $-1$: $-\frac{\zeta'(s)}{\zeta(s)} - \frac{1}{s-1} = O(1)$.  -/)  (proof := /--  This follows from Theorem \ref{logDerivResidue} and Theorem \ref{riemannZetaResidue}.  -/)]theorem riemannZetaLogDerivResidue :     U  𝓝 1, BddAbove (norm ∘ (-(ζ' / ζ) - (fun s  (s - 1)⁻¹)) '' (U \ {1})) := by  obtain U,U_in_nhds, hU := riemannZetaResidue  have hU' : BddAbove (norm ∘ (ζ - fun s  1 * (s - 1)⁻¹) '' (U \ {1})) := by    simp only [Function.comp_apply, Pi.sub_apply, one_mul] at hU     exact hU  obtain V,V_in_nhds, V_is_open, hV := nonZeroOfBddAbove U_in_nhds one_ne_zero hU'  let W := V ∩ interior U  have hW :  s  W \ {1}, ζ s  0 := by    intro s hs    have s_in_V_diff : s  V \ {1} := hs.1.1, hs.2    exact hV s s_in_V_diff  have ζ_holc: HolomorphicOn ζ (W \ {1}) := by    intro y hy    simp only [Set.mem_sdiff, mem_singleton_iff] at hy    refine DifferentiableAt.differentiableWithinAt ?_    apply differentiableAt_riemannZeta hy.2  have W_in_nhds : W  𝓝 1 := by    refine inter_mem V_in_nhds ?_    exact interior_mem_nhds.mpr U_in_nhds  have := logDerivResidue'' hW ζ_holc W_in_nhds one_ne_zero  have HW : BddAbove (norm ∘ (ζ - fun s  (s - 1)⁻¹) '' (W \ {1})) := by    obtain c, hc := bddAbove_def.mp hU    apply bddAbove_def.mpr    use c    rintro y x, x_in_W, fxy    apply hc    exact x, interior_subset x_in_W.1.2, x_in_W.2, fxy  simp only [one_mul] at this  have aux:  a, ‖-(deriv ζ a / ζ a) - (a - 1)⁻¹‖ = ‖(deriv ζ a / ζ a) + (a - 1)⁻¹‖ := by    intro a    calc-(deriv ζ a / ζ a) - (a - 1)⁻¹‖         =-((deriv ζ a / ζ a) + (a - 1)⁻¹)‖ := by ring_nf       _ = ‖(deriv ζ a / ζ a) + (a - 1)⁻¹‖ := by rw [norm_neg]  simp only [Function.comp_apply, Pi.sub_apply] at hU  simp only [Function.comp_apply, Pi.sub_apply, Pi.neg_apply, Pi.div_apply, aux]  apply this HW