English
The unit group αˣ is equipped with a negation that makes it a distributive neg ring under multiplication.
Русский
Группа единиц αˣ наделена отрицанием, образующим распределённое отрицательное кольцо под умножением.
LaTeX
$$$\text{HasDistribNeg}(\alpha^{\times})$ with $-u := ⟨-u, -u^{-1}, \dots\rangle$.$$
Lean4
/-- Each element of the group of units of a ring has an additive inverse. -/
instance : Neg αˣ :=
⟨fun u => ⟨-↑u, -↑u⁻¹, by simp, by simp⟩⟩