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Theorems · Theorem · commutative algebra

IsLocalRing.local_hom_TFAE

∀ {R : Type u_1} {S : Type u_2} [inst : CommSemiring R] [inst_1 : IsLocalRing R] [inst_2 : CommSemiring S]
  [inst_3 : IsLocalRing S] (f : R →+* S),
  [IsLocalHom f, ⇑f '' ↑(IsLocalRing.maximalIdeal R) ⊆ ↑(IsLocalRing.maximalIdeal S),
      Ideal.map f (IsLocalRing.maximalIdeal R) ≤ IsLocalRing.maximalIdeal S,
      IsLocalRing.maximalIdeal R ≤ Ideal.comap f (IsLocalRing.maximalIdeal S),
      Ideal.comap f (IsLocalRing.maximalIdeal S) = IsLocalRing.maximalIdeal R].TFAE

A ring homomorphism between local rings is a local ring hom iff it reflects units, i.e. any preimage of a unit is still a unit.

Defined in
Mathlib.RingTheory.LocalRing.RingHom.Basic
Cited by
10 results in Mathlib
Foundations
Depth 28 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes
CommSemiringIsLocalRingCommSemiringIsLocalRing

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