English
The map a ↦ single(a) defines a DistribMulActionSemiHom from M to α →₀ M, i.e., single acts compatibly with scalar multiplication.
Русский
Отображение a ↦ single(a) задаёт DistribMulActionSemiHom от M к α →₀ M, то есть single совместимо с масштабированием.
LaTeX
$$$\\text{single}(a): M \\to_+[R] α \\to_0 M$ и $\\text{map\_smul}'(k,m)$ отражает совместимость $k$-смуления.$$
Lean4
/-- `Finsupp.single` as a `DistribMulActionSemiHom`.
See also `Finsupp.lsingle` for the version as a linear map. -/
def single (a : α) : M →+[R] α →₀ M :=
{ singleAddHom a with map_smul' := fun k m => by simp }