English
The domain of evaluation forms an ideal again.
Русский
Область оценки образует идеал снова.
LaTeX
$$$\text{hasEvalIdeal is an ideal in } S$$$
Lean4
theorem hasSum_eval₂ (hφ : Continuous φ) (ha : HasEval a) (f : PowerSeries R) :
HasSum (fun (d : ℕ) ↦ φ (coeff d f) * a ^ d) (f.eval₂ φ a) :=
by
have := MvPowerSeries.hasSum_eval₂ hφ (hasEval ha) f
simp only [PowerSeries.eval₂]
rw [← (Finsupp.single_injective ()).hasSum_iff] at this
· convert this; simp; congr
· intro d hd
exact False.elim (hd ⟨d (), by ext; simp⟩)