English
For a maximal ideal I in a commutative ring R, the quotient R/I carries a division ring structure.
Русский
Для максимального идеала I в коммутативном кольце R фактор-кольцо R/I имеет структуру делительного кольца.
LaTeX
$$DivisionRing (R ⧸ I)$$
Lean4
/-- The quotient by a two-sided ideal that is maximal as a left ideal is a division ring.
This is a `def` rather than `instance`, since users
will have computable inverses (and `qsmul`, `ratCast`) in some applications.
See note [reducible non-instances]. -/
protected noncomputable abbrev divisionRing [I.IsMaximal] : DivisionRing (R ⧸ I) :=
fast_instance%{
__ := ring _
__ := Quotient.groupWithZero _
nnqsmul := _
nnqsmul_def _ _ := rfl
qsmul := _
qsmul_def _ _ := rfl }