English
If f: E → 𝕜 is differentiable at x and W is differentiable at x, then [V, f·W] = (Df f)(x)(Vx)·W(x) + f(x)·[V, W](x).
Русский
Если f: E → 𝕜 дифференцируема в x и W дифференцируема в x, то [V, f·W] = (Df f)(x)(Vx)·W(x) + f(x)·[V, W](x).
LaTeX
$$$\mathrm{lieBracketWithin}(V, f\cdot W) = (\mathrm{fderivWithin}\mathbb{K}f\, x)(Vx)\cdot Wx + f(x)\cdot \mathrm{lieBracketWithin}(V, W, s, x)$$$
Lean4
theorem lieBracket_const_smul_right {c : 𝕜} (hW : DifferentiableAt 𝕜 W x) :
lieBracket 𝕜 V (c • W) x = c • lieBracket 𝕜 V W x :=
by
simp only [← differentiableWithinAt_univ, ← lieBracketWithin_univ] at hW ⊢
exact lieBracketWithin_const_smul_right hW uniqueDiffWithinAt_univ