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Mathlib.RingTheory.GradedAlgebra.Homogeneous.Maps

Maps on homogeneous ideals #

In this file we define HomogeneousIdeal.map and HomogeneousIdeal.comap.

def HomogeneousIdeal.map {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) (I : HomogeneousIdeal 𝒜) :

Map a homogeneous ideal along a graded ring homomorphism. The underlying ideal is (definitionally) equal to Ideal.map.

Equations
Instances For
    def HomogeneousIdeal.comap {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) (I : HomogeneousIdeal ) :

    Pull back a homogeneous ideal along a graded ring homomorphism. The underlying ideal is (definitionally) equal to Ideal.comap, whose underlying set is definitionally equal to the preimage.

    Equations
    Instances For
      theorem HomogeneousIdeal.map_le_iff_le_comap {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) {I : HomogeneousIdeal 𝒜} {J : HomogeneousIdeal } :
      map f I J I comap f J
      theorem HomogeneousIdeal.le_comap_of_map_le {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) {I : HomogeneousIdeal 𝒜} {J : HomogeneousIdeal } :
      map f I JI comap f J

      Alias of the forward direction of HomogeneousIdeal.map_le_iff_le_comap.

      theorem HomogeneousIdeal.map_le_of_le_comap {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) {I : HomogeneousIdeal 𝒜} {J : HomogeneousIdeal } :
      I comap f Jmap f I J

      Alias of the reverse direction of HomogeneousIdeal.map_le_iff_le_comap.

      theorem HomogeneousIdeal.gc_map_comap {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) :
      theorem HomogeneousIdeal.map_mono {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) :
      theorem HomogeneousIdeal.comap_mono {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) :
      @[simp]
      theorem HomogeneousIdeal.toIdeal_comap {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) {J : HomogeneousIdeal } :
      @[simp]
      theorem HomogeneousIdeal.coe_comap {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) {J : HomogeneousIdeal } :
      (comap f J) = f ⁻¹' J
      @[simp]
      theorem HomogeneousIdeal.toIdeal_map {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) {I : HomogeneousIdeal 𝒜} :
      instance HomogeneousIdeal.isPrime_comap {A : Type u_1} {B : Type u_2} {σ : Type u_4} {τ : Type u_5} {ι : Type u_7} [Semiring A] [Semiring B] [SetLike σ A] [SetLike τ B] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} [GradedRing 𝒜] [GradedRing ] (f : 𝒜 →+*ᵍ ) {J : HomogeneousIdeal } [J.toIdeal.IsPrime] :
      @[simp]
      theorem HomogeneousIdeal.map_id {A : Type u_1} {σ : Type u_4} {ι : Type u_7} [Semiring A] [SetLike σ A] [AddSubmonoidClass σ A] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} [GradedRing 𝒜] {I : HomogeneousIdeal 𝒜} :
      theorem HomogeneousIdeal.map_map {A : Type u_1} {B : Type u_2} {C : Type u_3} {σ : Type u_4} {τ : Type u_5} {ω : Type u_6} {ι : Type u_7} [Semiring A] [Semiring B] [Semiring C] [SetLike σ A] [SetLike τ B] [SetLike ω C] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [AddSubmonoidClass ω C] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} {𝒞 : ιω} [GradedRing 𝒜] [GradedRing ] [GradedRing 𝒞] (f : 𝒜 →+*ᵍ ) (g : →+*ᵍ 𝒞) {I : HomogeneousIdeal 𝒜} :
      map g (map f I) = map (g.comp f) I
      theorem HomogeneousIdeal.map_comp {A : Type u_1} {B : Type u_2} {C : Type u_3} {σ : Type u_4} {τ : Type u_5} {ω : Type u_6} {ι : Type u_7} [Semiring A] [Semiring B] [Semiring C] [SetLike σ A] [SetLike τ B] [SetLike ω C] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [AddSubmonoidClass ω C] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} {𝒞 : ιω} [GradedRing 𝒜] [GradedRing ] [GradedRing 𝒞] (f : 𝒜 →+*ᵍ ) (g : →+*ᵍ 𝒞) {I : HomogeneousIdeal 𝒜} :
      map (g.comp f) I = map g (map f I)
      @[simp]
      theorem HomogeneousIdeal.comap_id {A : Type u_1} {σ : Type u_4} {ι : Type u_7} [Semiring A] [SetLike σ A] [AddSubmonoidClass σ A] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} [GradedRing 𝒜] {I : HomogeneousIdeal 𝒜} :
      theorem HomogeneousIdeal.comap_comap {A : Type u_1} {B : Type u_2} {C : Type u_3} {σ : Type u_4} {τ : Type u_5} {ω : Type u_6} {ι : Type u_7} [Semiring A] [Semiring B] [Semiring C] [SetLike σ A] [SetLike τ B] [SetLike ω C] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [AddSubmonoidClass ω C] [DecidableEq ι] [AddMonoid ι] {𝒜 : ισ} { : ιτ} {𝒞 : ιω} [GradedRing 𝒜] [GradedRing ] [GradedRing 𝒞] (f : 𝒜 →+*ᵍ ) (g : →+*ᵍ 𝒞) {K : HomogeneousIdeal 𝒞} :
      comap f (comap g K) = comap (g.comp f) K
      theorem HomogeneousIdeal.irrelevant_le_map_comp {A : Type u_1} {B : Type u_2} {C : Type u_3} {σ : Type u_4} {τ : Type u_5} {ω : Type u_6} {ι : Type u_7} [Semiring A] [Semiring B] [Semiring C] [SetLike σ A] [SetLike τ B] [SetLike ω C] [AddSubmonoidClass σ A] [AddSubmonoidClass τ B] [AddSubmonoidClass ω C] [DecidableEq ι] [AddCommMonoid ι] [PartialOrder ι] [CanonicallyOrderedAdd ι] {𝒜 : ισ} { : ιτ} {𝒞 : ιω} [GradedRing 𝒜] [GradedRing ] [GradedRing 𝒞] {f : 𝒜 →+*ᵍ } {g : →+*ᵍ 𝒞} (hf : irrelevant map f (irrelevant 𝒜)) (hg : irrelevant 𝒞 map g (irrelevant )) :
      irrelevant 𝒞 map (g.comp f) (irrelevant 𝒜)