English
A commuting family of symmetric linear maps on a finite-dimensional inner product space is simultaneously diagonalizable.
Русский
Коммутирующаяся семейство симметричных линейных отображений в конечном размере диагонализуется одновременно.
LaTeX
$$$\bigvee_{\chi} \bigwedge_{i} \operatorname{Eig}(T_i, \chi(i)) = \top$$$
Lean4
/-- Expression of `bilinearIteratedFDerivWithinTwo` in terms of `iteratedFDerivWithin`.
-/
theorem bilinearIteratedFDerivWithinTwo_eq_iteratedFDeriv {e : E} {s : Set E} (f : E → F) (hs : UniqueDiffOn 𝕜 s)
(he : e ∈ s) (e₁ e₂ : E) :
bilinearIteratedFDerivWithinTwo 𝕜 f s e e₁ e₂ = iteratedFDerivWithin 𝕜 2 f s e ![e₁, e₂] := by
simp [iteratedFDerivWithin_two_apply f hs he ![e₁, e₂], bilinearIteratedFDerivWithinTwo]