Pointwise operations of sets #
This file defines pointwise algebraic operations on sets.
Main declarations #
For sets s and t and scalar a:
s * t: Multiplication, set of allx * ywherex ∈ sandy ∈ t.s + t: Addition, set of allx + ywherex ∈ sandy ∈ t.s⁻¹: Inversion, set of allx⁻¹wherex ∈ s.-s: Negation, set of all-xwherex ∈ s.s / t: Division, set of allx / ywherex ∈ sandy ∈ t.s - t: Subtraction, set of allx - ywherex ∈ sandy ∈ t.s • t: Scalar multiplication, set of allx • ywherex ∈ sandy ∈ t.s +ᵥ t: Scalar addition, set of allx +ᵥ ywherex ∈ sandy ∈ t.s -ᵥ t: Scalar subtraction, set of allx -ᵥ ywherex ∈ sandy ∈ t.a • s: Scaling, set of alla • xwherex ∈ s.a +ᵥ s: Translation, set of alla +ᵥ xwherex ∈ s.
For α a semigroup/monoid, Set α is a semigroup/monoid.
As an unfortunate side effect, this means that n • s, where n : ℕ, is ambiguous between
pointwise scaling and repeated pointwise addition; the former has (2 : ℕ) • {1, 2} = {2, 4}, while
the latter has (2 : ℕ) • {1, 2} = {2, 3, 4}. See note [pointwise nat action].
Appropriate definitions and results are also transported to the additive theory via to_additive.
Implementation notes #
- The following expressions are considered in simp-normal form in a group:
(fun h ↦ h * g) ⁻¹' s,(fun h ↦ g * h) ⁻¹' s,(fun h ↦ h * g⁻¹) ⁻¹' s,(fun h ↦ g⁻¹ * h) ⁻¹' s,s * t,s⁻¹,(1 : Set _)(and similarly for additive variants). Expressions equal to one of these will be simplified. - We put all instances in the locale
Pointwise, so that these instances are not available by default. Note that we do not mark them as reducible (as argued by note [reducible non-instances]) since we expect the locale to be open whenever the instances are actually used (and making the instances reducible changes the behavior ofsimp.
Tags #
set multiplication, set addition, pointwise addition, pointwise multiplication, pointwise subtraction
0/1 as sets #
The singleton operation as a OneHom.
Equations
- Set.singletonOneHom = { toFun := singleton, map_one' := ⋯ }
Instances For
The singleton operation as a ZeroHom.
Equations
- Set.singletonZeroHom = { toFun := singleton, map_zero' := ⋯ }
Instances For
Set negation/inversion #
Equations
Equations
Set addition/multiplication #
The singleton operation as a MulHom.
Equations
- Set.singletonMulHom = { toFun := singleton, map_mul' := ⋯ }
Instances For
The singleton operation as an AddHom.
Equations
- Set.singletonAddHom = { toFun := singleton, map_add' := ⋯ }
Instances For
Set subtraction/division #
Translation/scaling of sets #
Repeated pointwise multiplication/division (not the same as pointwise repeated
multiplication/division!) of a Set. See note [pointwise nat action].
Instances For
Set α is an AddCommSemigroup under pointwise operations if α is.
Equations
Instances For
The singleton operation as a MonoidHom.
Equations
- Set.singletonMonoidHom = { toFun := Set.singletonMulHom.toFun, map_one' := ⋯, map_mul' := ⋯ }
Instances For
The singleton operation as an AddMonoidHom.
Equations
- Set.singletonAddMonoidHom = { toFun := Set.singletonAddHom.toFun, map_zero' := ⋯, map_add' := ⋯ }
Instances For
Set α is a Monoid under pointwise operations if α is.
Equations
- Set.monoid = Monoid.mk ⋯ ⋯ npowRecAuto ⋯ ⋯
Instances For
Set α is an AddMonoid under pointwise operations if α is.
Equations
- Set.addMonoid = AddMonoid.mk ⋯ ⋯ nsmulRecAuto ⋯ ⋯
Instances For
Set α is a subtraction monoid under pointwise operations if α is.
Equations
Instances For
Set α is a commutative division monoid under pointwise operations if α is.
Equations
Instances For
Set α is a commutative subtraction monoid under pointwise operations if α is.
Equations
Instances For
Alias of the reverse direction of Set.not_one_mem_div_iff.