Theorems · Theorem · complex analysis

AnalyticAt.eventually_eq_zero_or_eventually_ne_zero

∀ {𝕜 : Type u_1} [inst : NontriviallyNormedField 𝕜] {E : Type u_2} [inst_1 : NormedAddCommGroup E]
  [inst_2 : NormedSpace 𝕜 E] {f : 𝕜 → E} {z₀ : 𝕜},
  AnalyticAt 𝕜 f z₀ → (∀ᶠ (z : 𝕜) in nhds z₀, f z = 0) ∨ ∀ᶠ (z : 𝕜) in nhdsWithin z₀ {z₀}ᶜ, f z ≠ 0

The principle of isolated zeros for an analytic function, local version: if a function is analytic at z₀, then either it is identically zero in a neighborhood of z₀, or it does not vanish in a punctured neighborhood of z₀.

Defined in

Mathlib.Analysis.Analytic.IsolatedZeros

Cited by

6 results in Mathlib

Foundations

Depth 189 from the axioms · uses propext, Classical.choice, Quot.sound

Assumes

NontriviallyNormedFieldNormedAddCommGroupNormedSpace