Base-change properties of induced quotient maps #
For a ring homomorphism f : A →+* B, the induced map A/I → B/IB is a base change
of f. Hence it inherits every ring-homomorphism property stable under base change and
isomorphism. This applies, in particular, to faithful flatness and finite presentation.
theorem
RingHom.IsStableUnderBaseChange.quotientMap
{P : {A B : Type u} → [inst : CommRing A] → [inst_1 : CommRing B] → (A →+* B) → Prop}
(hP : IsStableUnderBaseChange fun {R S : Type u} [CommRing R] [CommRing S] => P)
(hiso : RespectsIso fun {R S : Type u} [CommRing R] [CommRing S] => P)
{A B : Type u}
[CommRing A]
[CommRing B]
(f : A →+* B)
(I : Ideal A)
(hf : P f)
:
P (Ideal.quotientMap (Ideal.map f I) f ⋯)
A property stable under base change and isomorphism passes from f : A →+* B to
A/I → B/IB.