English
For f: α' → α, the linear combination over α' with v∘f equals the composition of the linearCombination over α with the domain-mapping lmapDomain.
Русский
Для отображения f: α' → α линейная комбинация над α с v∘f равна композиции линейной комбинации над α с отображением lmapDomain.
LaTeX
$$$\\operatorname{linearCombination}_R (v \\circ f) = (\\operatorname{linearCombination}_R v) \\circ (\\mathrm{lmapDomain}\\, R\\, R\\, f)$$$
Lean4
theorem linearCombination_comp (f : α' → α) :
linearCombination R (v ∘ f) = (linearCombination R v).comp (lmapDomain R R f) :=
by
ext
simp [linearCombination_apply]