mathlib documentation

data.finsupp.pointwise

The pointwise product on finsupp. #

For the convolution product on finsupp when the domain has a binary operation, see the type synonyms add_monoid_algebra (which is in turn used to define polynomial and mv_polynomial) and monoid_algebra.

Declarations about the pointwise product on finsupps #

@[protected, instance]
noncomputable def finsupp.has_mul {α : Type u₁} {β : Type u₂} [mul_zero_class β] :
has_mul →₀ β)

The product of f g : α →₀ β is the finitely supported function whose value at a is f a * g a.

Equations
@[simp]
theorem finsupp.mul_apply {α : Type u₁} {β : Type u₂} [mul_zero_class β] {g₁ g₂ : α →₀ β} {a : α} :
(g₁ * g₂) a = (g₁ a) * g₂ a
theorem finsupp.support_mul {α : Type u₁} {β : Type u₂} [mul_zero_class β] [decidable_eq α] {g₁ g₂ : α →₀ β} :
(g₁ * g₂).support g₁.support g₂.support
@[protected, instance]
noncomputable def finsupp.mul_zero_class {α : Type u₁} {β : Type u₂} [mul_zero_class β] :
Equations
@[protected, instance]
noncomputable def finsupp.semigroup_with_zero {α : Type u₁} {β : Type u₂} [semigroup_with_zero β] :
Equations
@[protected, instance]
noncomputable def finsupp.pointwise_module {α : Type u₁} {β : Type u₂} [semiring β] :
module (α → β) →₀ β)

The pointwise multiplicative action of functions on finitely supported functions

Equations
@[simp]
theorem finsupp.coe_pointwise_module {α : Type u₁} {β : Type u₂} [semiring β] (f : α → β) (g : α →₀ β) :
(f g) = f g