English
Mapping the alphabet of a language by a function f yields a ring homomorphism between language algebras.
Русский
Отображение алфавита языка функцией f образует гомоморфизм колец между алгебрами языков.
LaTeX
$$$ \text{map} : (\alpha \to \beta) \to \text{RingHom}(\text{Language } \alpha, \text{Language } \beta) $$$
Lean4
/-- Maps the alphabet of a language. -/
def map (f : α → β) : Language α →+* Language β
where
toFun := image (List.map f)
map_zero' := image_empty _
map_one' := image_singleton
map_add' := image_union _
map_mul' _ _ := image_image2_distrib <| fun _ _ => map_append