Prod instances for additive and multiplicative actions

This file defines instances for binary product of additive and multiplicative actions and provides scalar multiplication as a homomorphism from α × β to β.

Main declarations

• smulMulHom/smulMonoidHom: Scalar multiplication bundled as a multiplicative/monoid homomorphism.

See also

• Mathlib/Algebra/Group/Action/Option.lean
• Mathlib/Algebra/Group/Action/Pi.lean
• Mathlib/Algebra/Group/Action/Sigma.lean
• Mathlib/Algebra/Group/Action/Sum.lean

Porting notes

The to_additive attribute can be used to generate both the smul and vadd lemmas from the corresponding pow lemmas, as explained on zulip here: https://leanprover.zulipchat.com/#narrow/near/316087838

This was not done as part of the port in order to stay as close as possible to the mathlib3 code.

instance Prod.isScalarTower {M : Type u_1} {N : Type u_2} {α : Type u_5} {β : Type u_6} [SMul M α] [SMul M β] [SMul N α] [SMul N β] [SMul M N] [IsScalarTower M N α] [IsScalarTower M N β] : IsScalarTower M N (α × β)

instance Prod.vaddAssocClass {M : Type u_1} {N : Type u_2} {α : Type u_5} {β : Type u_6} [VAdd M α] [VAdd M β] [VAdd N α] [VAdd N β] [VAdd M N] [VAddAssocClass M N α] [VAddAssocClass M N β] : VAddAssocClass M N (α × β)

instance Prod.smulCommClass {M : Type u_1} {N : Type u_2} {α : Type u_5} {β : Type u_6} [SMul M α] [SMul M β] [SMul N α] [SMul N β] [SMulCommClass M N α] [SMulCommClass M N β] : SMulCommClass M N (α × β)

instance Prod.vaddCommClass {M : Type u_1} {N : Type u_2} {α : Type u_5} {β : Type u_6} [VAdd M α] [VAdd M β] [VAdd N α] [VAdd N β] [VAddCommClass M N α] [VAddCommClass M N β] : VAddCommClass M N (α × β)

instance Prod.isCentralScalar {M : Type u_1} {α : Type u_5} {β : Type u_6} [SMul M α] [SMul M β] [SMul Mᵐᵒᵖ α] [SMul Mᵐᵒᵖ β] [IsCentralScalar M α] [IsCentralScalar M β] : IsCentralScalar M (α × β)

instance Prod.isCentralVAdd {M : Type u_1} {α : Type u_5} {β : Type u_6} [VAdd M α] [VAdd M β] [VAdd Mᵃᵒᵖ α] [VAdd Mᵃᵒᵖ β] [IsCentralVAdd M α] [IsCentralVAdd M β] : IsCentralVAdd M (α × β)

instance Prod.faithfulSMulLeft {M : Type u_1} {α : Type u_5} {β : Type u_6} [SMul M α] [SMul M β] [FaithfulSMul M α] [Nonempty β] : FaithfulSMul M (α × β)

instance Prod.faithfulVAddLeft {M : Type u_1} {α : Type u_5} {β : Type u_6} [VAdd M α] [VAdd M β] [FaithfulVAdd M α] [Nonempty β] : FaithfulVAdd M (α × β)

instance Prod.faithfulSMulRight {M : Type u_1} {α : Type u_5} {β : Type u_6} [SMul M α] [SMul M β] [Nonempty α] [FaithfulSMul M β] : FaithfulSMul M (α × β)

instance Prod.faithfulVAddRight {M : Type u_1} {α : Type u_5} {β : Type u_6} [VAdd M α] [VAdd M β] [Nonempty α] [FaithfulVAdd M β] : FaithfulVAdd M (α × β)

instance Prod.smulCommClassBoth {M : Type u_1} {N : Type u_2} {P : Type u_3} [Mul N] [Mul P] [SMul M N] [SMul M P] [SMulCommClass M N N] [SMulCommClass M P P] : SMulCommClass M (N × P) (N × P)

instance Prod.vaddCommClassBoth {M : Type u_1} {N : Type u_2} {P : Type u_3} [Add N] [Add P] [VAdd M N] [VAdd M P] [VAddCommClass M N N] [VAddCommClass M P P] : VAddCommClass M (N × P) (N × P)

instance Prod.isScalarTowerBoth {M : Type u_1} {N : Type u_2} {P : Type u_3} [Mul N] [Mul P] [SMul M N] [SMul M P] [IsScalarTower M N N] [IsScalarTower M P P] : IsScalarTower M (N × P) (N × P)

instance Prod.mulAction {M : Type u_1} {α : Type u_5} {β : Type u_6} [Monoid M] [MulAction M α] [MulAction M β] : MulAction M (α × β)

Equations

• Prod.mulAction = { toSMul := Prod.instSMul, one_smul := ⋯, mul_smul := ⋯ }

instance Prod.addAction {M : Type u_1} {α : Type u_5} {β : Type u_6} [AddMonoid M] [AddAction M α] [AddAction M β] : AddAction M (α × β)

Equations

• Prod.addAction = { toVAdd := Prod.instVAdd, zero_vadd := ⋯, add_vadd := ⋯ }

Scalar multiplication as a homomorphism

def smulMulHom {α : Type u_5} {β : Type u_6} [Monoid α] [Mul β] [MulAction α β] [IsScalarTower α β β] [SMulCommClass α β β] : α × β →ₙ* β

Scalar multiplication as a multiplicative homomorphism.

Equations

• smulMulHom = { toFun := fun (a : α × β) => a.1 • a.2, map_mul' := ⋯ }

@[simp]

theorem smulMulHom_apply {α : Type u_5} {β : Type u_6} [Monoid α] [Mul β] [MulAction α β] [IsScalarTower α β β] [SMulCommClass α β β] (a : α × β) : smulMulHom a = a.1 • a.2

def smulMonoidHom {α : Type u_5} {β : Type u_6} [Monoid α] [MulOneClass β] [MulAction α β] [IsScalarTower α β β] [SMulCommClass α β β] : α × β →* β

Scalar multiplication as a monoid homomorphism.

Equations

• smulMonoidHom = { toFun := smulMulHom.toFun, map_one' := ⋯, map_mul' := ⋯ }

@[simp]

theorem smulMonoidHom_apply {α : Type u_5} {β : Type u_6} [Monoid α] [MulOneClass β] [MulAction α β] [IsScalarTower α β β] [SMulCommClass α β β] (a✝ : α × β) : smulMonoidHom a✝ = smulMulHom.toFun a✝

@[reducible, inline]

abbrev MulAction.prodOfSMulCommClass (M : Type u_1) (N : Type u_2) (α : Type u_5) [Monoid M] [Monoid N] [MulAction M α] [MulAction N α] [SMulCommClass M N α] : MulAction (M × N) α

Construct a MulAction by a product monoid from MulActions by the factors. This is not an instance to avoid diamonds for example when α := M × N.

Equations

• MulAction.prodOfSMulCommClass M N α = { smul := fun (mn : M × N) (a : α) => mn.1 • mn.2 • a, one_smul := ⋯, mul_smul := ⋯ }

@[reducible, inline]

abbrev AddAction.prodOfVAddCommClass (M : Type u_1) (N : Type u_2) (α : Type u_5) [AddMonoid M] [AddMonoid N] [AddAction M α] [AddAction N α] [VAddCommClass M N α] : AddAction (M × N) α

Construct an AddAction by a product monoid from AddActions by the factors. This is not an instance to avoid diamonds for example when α := M × N.

Equations

• AddAction.prodOfVAddCommClass M N α = { vadd := fun (mn : M × N) (a : α) => mn.1 +ᵥ mn.2 +ᵥ a, zero_vadd := ⋯, add_vadd := ⋯ }

def MulAction.prodEquiv (M : Type u_1) (N : Type u_2) (α : Type u_5) [Monoid M] [Monoid N] : MulAction (M × N) α ≃ (x : MulAction M α) ×' (x_1 : MulAction N α) ×' SMulCommClass M N α

A MulAction by a product monoid is equivalent to commuting MulActions by the factors.

Equations

• One or more equations did not get rendered due to their size.

def AddAction.prodEquiv (M : Type u_1) (N : Type u_2) (α : Type u_5) [AddMonoid M] [AddMonoid N] : AddAction (M × N) α ≃ (x : AddAction M α) ×' (x_1 : AddAction N α) ×' VAddCommClass M N α

An AddAction by a product monoid is equivalent to commuting AddActions by the factors.

Equations

• One or more equations did not get rendered due to their size.