Partitions of rectangular boxes in ℝⁿ #
In this file we define (pre)partitions of rectangular boxes in ℝⁿ. A partition of a box I in
ℝⁿ (see BoxIntegral.Prepartition and BoxIntegral.Prepartition.IsPartition) is a finite set
of pairwise disjoint boxes such that their union is exactly I. We use boxes : Finset (Box ι) to
store the set of boxes.
Many lemmas about box integrals deal with pairwise disjoint collections of subboxes, so we define a
structure BoxIntegral.Prepartition (I : BoxIntegral.Box ι) that stores a collection of boxes
such that
- each box
J ∈ boxesis a subbox ofI; - the boxes are pairwise disjoint as sets in
ℝⁿ.
Then we define a predicate BoxIntegral.Prepartition.IsPartition; π.IsPartition means that the
boxes of π actually cover the whole I. We also define some operations on prepartitions:
BoxIntegral.Prepartition.biUnion: split each box of a partition into smaller boxes;BoxIntegral.Prepartition.restrict: restrict a partition to a smaller box.
We also define a SemilatticeInf structure on BoxIntegral.Prepartition I for all
I : BoxIntegral.Box ι.
Tags #
rectangular box, partition
- boxes : Finset (BoxIntegral.Box ι)
- le_of_mem' : ∀ (J : BoxIntegral.Box ι), J ∈ s.boxes → J ≤ I
- pairwiseDisjoint : Set.Pairwise (↑s.boxes) (Disjoint on BoxIntegral.Box.toSet)
A prepartition of I : BoxIntegral.Box ι is a finite set of pairwise disjoint subboxes of
I.
Instances For
The singleton prepartition {J}, J ≤ I.
Equations
- One or more equations did not get rendered due to their size.
Instances For
We say that π ≤ π' if each box of π is a subbox of some box of π'.
Equations
- BoxIntegral.Prepartition.partialOrder = PartialOrder.mk (_ : ∀ (π₁ π₂ : BoxIntegral.Prepartition I), π₁ ≤ π₂ → π₂ ≤ π₁ → π₁ = π₂)
Equations
- BoxIntegral.Prepartition.instOrderTopPrepartitionInstLEPrepartition = OrderTop.mk (_ : ∀ (π : BoxIntegral.Prepartition I) (J : BoxIntegral.Box ι), J ∈ π → ∃ I', I' ∈ ⊤ ∧ J ≤ I')
Equations
- BoxIntegral.Prepartition.instOrderBotPrepartitionInstLEPrepartition = OrderBot.mk (_ : ∀ (x : BoxIntegral.Prepartition I) (x_1 : BoxIntegral.Box ι), x_1 ∈ ⊥ → ∃ I', I' ∈ x ∧ x_1 ≤ I')
An auxiliary lemma used to prove that the same point can't belong to more than
2 ^ Fintype.card ι closed boxes of a prepartition.
The set of boxes of a prepartition that contain x in their closures has cardinality
at most 2 ^ Fintype.card ι.
Given a prepartition π : BoxIntegral.Prepartition I, π.iUnion is the part of I covered by
the boxes of π.
Equations
- BoxIntegral.Prepartition.iUnion π = ⋃ (J : BoxIntegral.Box ι) (_ : J ∈ π), ↑J
Instances For
Given a prepartition π of a box I and a collection of prepartitions πi J of all boxes
J ∈ π, returns the prepartition of I into the union of the boxes of all πi J.
Though we only use the values of πi on the boxes of π, we require πi to be a globally defined
function.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Given a box J ∈ π.biUnion πi, returns the box J' ∈ π such that J ∈ πi J'.
For J ∉ π.biUnion πi, returns I.
Equations
- BoxIntegral.Prepartition.biUnionIndex π πi J = if hJ : J ∈ BoxIntegral.Prepartition.biUnion π πi then Exists.choose (_ : ∃ J', J' ∈ π ∧ J ∈ πi J') else I
Instances For
Uniqueness property of BoxIntegral.Prepartition.biUnionIndex.
Create a BoxIntegral.Prepartition from a collection of possibly empty boxes by filtering out
the empty one if it exists.
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Instances For
Restrict a prepartition to a box.
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Instances For
Restricting to a larger box does not change the set of boxes. We cannot claim equality of prepartitions because they have different types.
Equations
- BoxIntegral.Prepartition.inf = { inf := fun π₁ π₂ => BoxIntegral.Prepartition.biUnion π₁ fun J => BoxIntegral.Prepartition.restrict π₂ J }
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- One or more equations did not get rendered due to their size.
The prepartition with boxes {J ∈ π | p J}.
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- One or more equations did not get rendered due to their size.
Instances For
Union of two disjoint prepartitions.
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- One or more equations did not get rendered due to their size.
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The distortion of a prepartition is the maximum of the distortions of the boxes of this prepartition.
Equations
- BoxIntegral.Prepartition.distortion π = Finset.sup π.boxes BoxIntegral.Box.distortion
Instances For
A prepartition π of I is a partition if the boxes of π cover the whole I.