English
For x in Additive X, the neighborhood at x.toMul equals the pushforward by toMul of the neighborhood at x.
Русский
Для x в Additive X окрестности в x.toMul равны образу окрестностей x под действием toMul.
LaTeX
$$$\forall x \in \mathrm{Additive}\,X,\ \mathcal{N}(x^{\mathrm{toMul}}) = \operatorname{map}(\mathrm{toMul})(\mathcal{N}(x))$$$
Lean4
theorem nhds_toMul (x : Additive X) : 𝓝 x.toMul = map toMul (𝓝 x) :=
rfl