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Rename homMulEquiv to endMulEquiv
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Vierkantor committed Dec 2, 2024
1 parent 656f2c3 commit d34a272
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Showing 4 changed files with 11 additions and 11 deletions.
2 changes: 1 addition & 1 deletion Mathlib/Algebra/Category/ModuleCat/Basic.lean
Original file line number Diff line number Diff line change
Expand Up @@ -420,7 +420,7 @@ variable (M N : ModuleCat.{v} R)

/-- `ModuleCat.Hom.hom` as an isomorphism of monoids. -/
@[simps]
def homMulEquiv : End M ≃* (M →ₗ[R] M) where
def endMulEquiv : End M ≃* (M →ₗ[R] M) where
toFun := ModuleCat.Hom.hom
invFun := ModuleCat.asHom
map_mul' _ _ := rfl
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2 changes: 1 addition & 1 deletion Mathlib/RepresentationTheory/Character.lean
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Expand Up @@ -116,7 +116,7 @@ theorem char_orthonormal (V W : FDRep k G) [Simple V] [Simple W] :
rw [char_iso (FDRep.dualTensorIsoLinHom W.ρ V)]
-- The average over the group of the character of a representation equals the dimension of the
-- space of invariants.
rw [average_char_eq_finrank_invariants, ← FDRep.homMulEquiv_comp_ρ (of _),
rw [average_char_eq_finrank_invariants, ← FDRep.endMulEquiv_comp_ρ (of _),
FDRep.of_ρ (linHom W.ρ V.ρ)]
-- The space of invariants of `Hom(W, V)` is the subspace of `G`-equivariant linear maps,
-- `Hom_G(W, V)`.
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12 changes: 6 additions & 6 deletions Mathlib/RepresentationTheory/FDRep.lean
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Expand Up @@ -82,15 +82,15 @@ instance (V W : FDRep k G) : FiniteDimensional k (V ⟶ W) :=

/-- The monoid homomorphism corresponding to the action of `G` onto `V : FDRep k G`. -/
def ρ (V : FDRep k G) : G →* V →ₗ[k] V :=
(ModuleCat.homMulEquiv _).toMonoidHom.comp (Action.ρ V)
(ModuleCat.endMulEquiv _).toMonoidHom.comp (Action.ρ V)

@[simp]
lemma homMulEquiv_symm_comp_ρ (V : FDRep k G) :
(MonoidHomClass.toMonoidHom (ModuleCat.homMulEquiv V.V.obj).symm).comp (ρ V) = Action.ρ V := rfl
lemma endMulEquiv_symm_comp_ρ (V : FDRep k G) :
(MonoidHomClass.toMonoidHom (ModuleCat.endMulEquiv V.V.obj).symm).comp (ρ V) = Action.ρ V := rfl

@[simp]
lemma homMulEquiv_comp_ρ (V : FDRep k G) :
(MonoidHomClass.toMonoidHom (ModuleCat.homMulEquiv V.V.obj)).comp (Action.ρ V) = ρ V := rfl
lemma endMulEquiv_comp_ρ (V : FDRep k G) :
(MonoidHomClass.toMonoidHom (ModuleCat.endMulEquiv V.V.obj)).comp (Action.ρ V) = ρ V := rfl

@[simp]
lemma hom_action_ρ (V : FDRep k G) (g : G) : (Action.ρ V g).hom = ρ V g := rfl
Expand All @@ -111,7 +111,7 @@ theorem Iso.conj_ρ {V W : FDRep k G} (i : V ≅ W) (g : G) :
@[simps ρ]
def of {V : Type u} [AddCommGroup V] [Module k V] [FiniteDimensional k V]
(ρ : Representation k G V) : FDRep k G :=
⟨FGModuleCat.of k V, ρ ≫ MonCat.ofHom (ModuleCat.homMulEquiv _).symm.toMonoidHom⟩
⟨FGModuleCat.of k V, ρ ≫ MonCat.ofHom (ModuleCat.endMulEquiv _).symm.toMonoidHom⟩

instance : HasForget₂ (FDRep k G) (Rep k G) where
forget₂ := (forget₂ (FGModuleCat k) (ModuleCat k)).mapAction (MonCat.of G)
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6 changes: 3 additions & 3 deletions Mathlib/RepresentationTheory/Rep.lean
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Expand Up @@ -61,11 +61,11 @@ instance (V : Rep k G) : Module k V := by
-/
def ρ (V : Rep k G) : Representation k G V :=
-- Porting note: was `V.ρ`
(ModuleCat.homMulEquiv V.V).toMonoidHom.comp (Action.ρ V)
(ModuleCat.endMulEquiv V.V).toMonoidHom.comp (Action.ρ V)

/-- Lift an unbundled representation to `Rep`. -/
def of {V : Type u} [AddCommGroup V] [Module k V] (ρ : G →* V →ₗ[k] V) : Rep k G :=
⟨ModuleCat.of k V, MonCat.ofHom ((ModuleCat.homMulEquiv _).symm.toMonoidHom.comp ρ) ⟩
⟨ModuleCat.of k V, MonCat.ofHom ((ModuleCat.endMulEquiv _).symm.toMonoidHom.comp ρ) ⟩

@[simp]
theorem coe_of {V : Type u} [AddCommGroup V] [Module k V] (ρ : G →* V →ₗ[k] V) :
Expand All @@ -77,7 +77,7 @@ theorem of_ρ {V : Type u} [AddCommGroup V] [Module k V] (ρ : G →* V →ₗ[k
rfl

theorem Action_ρ_eq_ρ {A : Rep k G} :
Action.ρ A = (ModuleCat.homMulEquiv _).symm.toMonoidHom.comp A.ρ :=
Action.ρ A = (ModuleCat.endMulEquiv _).symm.toMonoidHom.comp A.ρ :=
rfl

@[simp]
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