English
The logarithm provides an order isomorphism between the unit group Gᵐ⁰ˣ and G, i.e., log: Gᵐ⁰ˣ → G is an order-preserving bijection with exp as inverse.
Русский
Логарифм задаёт упорядоченное тождество между единицами в WithZero и G: log: G^{×}_{0} → G — биекция, сохраниющая порядок, обратной связью служит exp.
LaTeX
$$$\log: G^{\times}_{0} \xrightarrow{\sim}_{\text{ord}} G\,.$$$
Lean4
/-- The logarithm as an order isomorphism between `Gᵐ⁰ˣ` and `G`. -/
@[simps!]
def logOrderIso : Gᵐ⁰ˣ ≃o G where
__ := logEquiv
map_rel_iff' := by simp