English
The exterior derivative of the sum ω1 + ω2 is the sum of exterior derivatives: extDeriv(ω1 + ω2) = extDeriv ω1 + extDeriv ω2.
Русский
Производная по 外 extDeriv суммы ω1 и ω2 равна сумме внешних производных.
LaTeX
$$$\text{extDerivWithin}(\omega_1 + \omega_2) = \text{extDerivWithin}(\omega_1) + \text{extDerivWithin}(\omega_2).$$$
Lean4
theorem extDerivWithin_add (hsx : UniqueDiffWithinAt 𝕜 s x) (hω₁ : DifferentiableWithinAt 𝕜 ω₁ s x)
(hω₂ : DifferentiableWithinAt 𝕜 ω₂ s x) :
extDerivWithin (ω₁ + ω₂) s x = extDerivWithin ω₁ s x + extDerivWithin ω₂ s x := by
simp [extDerivWithin, fderivWithin_add hsx hω₁ hω₂, alternatizeUncurryFin_add]