English
mk I a = 0 iff a ∈ I.
Русский
mk I a = 0 эквивалентно a ∈ I.
LaTeX
$$$mk_I(a) = 0 \\iff a \\in I$$$
Lean4
/-- The ring homomorphism from the quotient by a smaller ideal to the quotient by a larger ideal.
This is the `Ideal.Quotient` version of `Quot.Factor`
When the two ideals are of the form `I^m` and `I^n` and `n ≤ m`,
please refer to the dedicated version `Ideal.Quotient.factorPow`. -/
def factor (H : S ≤ T) : R ⧸ S →+* R ⧸ T :=
Ideal.Quotient.lift S (mk T) fun _ hx => eq_zero_iff_mem.2 (H hx)