English
The slope of the composed map f ∘ g equals the linear part of f applied to the slope of g: slope (f ∘ g) a b = f.linear (slope g a b).
Русский
Уклон композиции f ∘ g равен линейной части отображения f, примененной к уклону g: slope (f ∘ g) a b = f.linear (slope g a b).
LaTeX
$$$\operatorname{slope}(f \circ g)\ a\ b = f.linear \bigl(\operatorname{slope}(g)\ a\ b\bigr)$$$
Lean4
theorem slope_comp {F PF : Type*} [AddCommGroup F] [Module k F] [AddTorsor F PF] (f : PE →ᵃ[k] PF) (g : k → PE)
(a b : k) : slope (f ∘ g) a b = f.linear (slope g a b) := by
simp only [slope, (· ∘ ·), f.linear.map_smul, f.linearMap_vsub]