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.
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:
(λ h, h * g) ⁻¹' s,(λ h, g * h) ⁻¹' s,(λ h, h * g⁻¹) ⁻¹' s,(λ 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 #
Set negation/inversion #
The pointwise negation of set -s is defined as {x | -x ∈ s} in locale Pointwise.
It is equal to {-x | x ∈ s}, see Set.image_neg.
Equations
- Set.neg = { neg := Set.preimage Neg.neg }
Instances For
The pointwise inversion of set s⁻¹ is defined as {x | x⁻¹ ∈ s} in locale Pointwise. It is
equal to {x⁻¹ | x ∈ s}, see Set.image_inv.
Equations
- Set.inv = { inv := Set.preimage Inv.inv }
Instances For
Set addition/multiplication #
Set subtraction/division #
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 AddSemigroup under pointwise operations if α is.
Equations
- One or more equations did not get rendered due to their size.
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Set α is an AddCommSemigroup under pointwise operations if α is.
Equations
- One or more equations did not get rendered due to their size.
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Set α is a CommSemigroup under pointwise operations if α is.
Equations
- One or more equations did not get rendered due to their size.
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Set α is an AddZeroClass under pointwise operations if α is.
Equations
- One or more equations did not get rendered due to their size.
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Set α is a MulOneClass under pointwise operations if α is.
Equations
- One or more equations did not get rendered due to their size.
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The singleton operation as an AddMonoidHom.
Equations
- One or more equations did not get rendered due to their size.
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The singleton operation as a MonoidHom.
Equations
- One or more equations did not get rendered due to their size.
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Set α is a subtraction monoid under pointwise operations if α is.
Equations
- One or more equations did not get rendered due to their size.
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Set α is a division monoid under pointwise operations if α is.
Equations
- One or more equations did not get rendered due to their size.
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Set α is a commutative subtraction monoid under pointwise operations if α is.
Equations
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Set α is a commutative division monoid under pointwise operations if α is.
Equations
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Note that Set is not a MulZeroClass because 0 * ∅ ≠ 0.
Alias of the reverse direction of Set.not_one_mem_div_iff.
Equations
- (_ : motive h) = (_ : motive h)