English
The span of a singleton set equals the ideal generated by its element.
Русский
Замыкание множества с одним элементом образует порожденное им идеал.
LaTeX
$$$\mathrm{span}\,R(\{x\}) = \{ r\cdot x : r\in R\} = \mathrm{span}\,R\{x\}$$$
Lean4
/-- The action on a submodule corresponding to applying the action to every element.
This is available as an instance in the `Pointwise` locale.
This is a stronger version of `Submodule.pointwiseDistribMulAction`. -/
protected def pointwiseMulSemiringAction : MulSemiringAction α (Submodule R A)
where
__ := Submodule.pointwiseDistribMulAction
smul_mul r x y := Submodule.map_mul x y <| MulSemiringAction.toAlgHom R A r
smul_one r := Submodule.map_one <| MulSemiringAction.toAlgHom R A r