The set lattice and (pre)images of functions #
This file contains lemmas on the interaction between the indexed union/intersection of sets
and the image and preimage operations: Set.image, Set.preimage, Set.image2, Set.kernImage.
It also covers Set.MapsTo, Set.InjOn, Set.SurjOn, Set.BijOn.
In order to accommodate Set.image2, the file includes results on union/intersection in products.
Naming convention #
In lemma names,
⋃ i, s iis callediUnion⋂ i, s iis callediInter⋃ i j, s i jis callediUnion₂. This is aniUnioninside aniUnion.⋂ i j, s i jis callediInter₂. This is aniInterinside aniInter.⋃ i ∈ s, t iis calledbiUnionfor "boundediUnion". This is the special case ofiUnion₂wherej : i ∈ s.⋂ i ∈ s, t iis calledbiInterfor "boundediInter". This is the special case ofiInter₂wherej : i ∈ s.
Notation #
⋃:Set.iUnion⋂:Set.iInter⋃₀:Set.sUnion⋂₀:Set.sInter
theorem Set.image_preimage {α : Type u_1} {β : Type u_2} {f : α → β} :
GaloisConnection (image f) (preimage f)
theorem Set.preimage_kernImage {α : Type u_1} {β : Type u_2} {f : α → β} :
GaloisConnection (preimage f) (kernImage f)
Bounded unions and intersections #
Lemmas about Set.MapsTo #
restrictPreimage #
InjOn #
theorem Set.image_iInter {α : Type u_1} {β : Type u_2} {ι : Sort u_5} {f : α → β} (hf : Function.Bijective f) (s : ι → Set α) :
SurjOn #
BijOn #
image, preimage #
theorem Set.image2_eq_iUnion {α : Type u_1} {β : Type u_2} {γ : Type u_3} (f : α → β → γ) (s : Set α) (t : Set β) :
The Set.image2 version of Set.image_eq_iUnion