English
The toFinsupp map preserves finite sums: toFinsupp(∑ i∈s f i) = ∑ i∈s toFinsupp(f i).
Русский
Отображение toFinsupp сохраняет склейку по конечным суммам: toFinsupp( ∑ i∈s f(i) ) = ∑ i∈s toFinsupp(f(i)).
LaTeX
$$$\operatorname{toFinsupp}\Bigl(\sum_{i\in s} f_i\Bigr) = \sum_{i\in s} \operatorname{toFinsupp}(f_i)$$$
Lean4
/-- Linear isomorphism between `R[X]` and `R[ℕ]`. This is just an
implementation detail, but it can be useful to transfer results from `Finsupp` to polynomials. -/
@[simps!]
def toFinsuppIsoLinear : R[X] ≃ₗ[R] R[ℕ] where
__ := toFinsuppIso R
map_smul' _ _ := rfl