English
In the quotient by a monoid, the unit element is represented by the class of 1.
Русский
В фактор-группе по моноиду единица задаётся классом единицы в моноиде.
LaTeX
$$$1_{c} = 1$$$
Lean4
/-- The 1 of the quotient of a monoid by a congruence relation is the equivalence class of the
monoid's 1. -/
@[to_additive (attr := simp) /-- The 0 of the quotient of an `AddMonoid` by an additive congruence
relation is the equivalence class of the `AddMonoid`'s 0. -/
]
theorem coe_one : ((1 : M) : c.Quotient) = 1 :=
rfl