Compact sets #
We define a few types of compact sets in a topological space.
Main Definitions #
For a topological space α
,
TopologicalSpace.Compacts α
: The type of compact sets.TopologicalSpace.NonemptyCompacts α
: The type of non-empty compact sets.TopologicalSpace.PositiveCompacts α
: The type of compact sets with non-empty interior.TopologicalSpace.CompactOpens α
: The type of compact open sets. This is a central object in the study of spectral spaces.
Compact sets #
The type of compact sets of a topological space.
Instances For
Equations
- TopologicalSpace.Compacts.instSetLikeCompacts = { coe := TopologicalSpace.Compacts.carrier, coe_injective' := ⋯ }
See Note [custom simps projection].
Equations
Instances For
Equations
- ⋯ = ⋯
Equations
- ⋯ = ⋯
Equations
- TopologicalSpace.Compacts.instSupCompacts = { sup := fun (s t : TopologicalSpace.Compacts α) => { carrier := ↑s ∪ ↑t, isCompact' := ⋯ } }
Equations
- TopologicalSpace.Compacts.instInfCompacts = { inf := fun (s t : TopologicalSpace.Compacts α) => { carrier := ↑s ∩ ↑t, isCompact' := ⋯ } }
Equations
- TopologicalSpace.Compacts.instTopCompacts = { top := { carrier := Set.univ, isCompact' := ⋯ } }
Equations
- TopologicalSpace.Compacts.instSemilatticeSupCompacts = Function.Injective.semilatticeSup SetLike.coe ⋯ ⋯
Equations
- TopologicalSpace.Compacts.instDistribLatticeCompacts = Function.Injective.distribLattice SetLike.coe ⋯ ⋯ ⋯
Equations
- TopologicalSpace.Compacts.instOrderBotCompactsToLEToPreorderToPartialOrderInstSemilatticeSupCompacts = OrderBot.lift SetLike.coe ⋯ ⋯
Equations
- TopologicalSpace.Compacts.instBoundedOrderCompactsToLEToPreorderToPartialOrderInstSemilatticeSupCompacts = BoundedOrder.lift SetLike.coe ⋯ ⋯ ⋯
The type of compact sets is inhabited, with default element the empty set.
The image of a compact set under a continuous function.
Equations
- TopologicalSpace.Compacts.map f hf K = { carrier := f '' K.carrier, isCompact' := ⋯ }
Instances For
A homeomorphism induces an equivalence on compact sets, by taking the image.
Equations
- TopologicalSpace.Compacts.equiv f = { toFun := TopologicalSpace.Compacts.map ⇑f ⋯, invFun := TopologicalSpace.Compacts.map ⇑(Homeomorph.symm f) ⋯, left_inv := ⋯, right_inv := ⋯ }
Instances For
The image of a compact set under a homeomorphism can also be expressed as a preimage.
The product of two TopologicalSpace.Compacts
, as a TopologicalSpace.Compacts
in the product
space.
Equations
- TopologicalSpace.Compacts.prod K L = { carrier := ↑K ×ˢ ↑L, isCompact' := ⋯ }
Instances For
Nonempty compact sets #
The type of nonempty compact sets of a topological space.
- carrier : Set α
- isCompact' : IsCompact self.carrier
- nonempty' : Set.Nonempty self.carrier
Instances For
Equations
- TopologicalSpace.NonemptyCompacts.instSetLikeNonemptyCompacts = { coe := fun (s : TopologicalSpace.NonemptyCompacts α) => s.carrier, coe_injective' := ⋯ }
See Note [custom simps projection].
Equations
Instances For
Reinterpret a nonempty compact as a closed set.
Equations
- TopologicalSpace.NonemptyCompacts.toCloseds s = { carrier := ↑s, closed' := ⋯ }
Instances For
Equations
- TopologicalSpace.NonemptyCompacts.instSupNonemptyCompacts = { sup := fun (s t : TopologicalSpace.NonemptyCompacts α) => { toCompacts := s.toCompacts ⊔ t.toCompacts, nonempty' := ⋯ } }
Equations
- TopologicalSpace.NonemptyCompacts.instSemilatticeSupNonemptyCompacts = Function.Injective.semilatticeSup SetLike.coe ⋯ ⋯
Equations
- TopologicalSpace.NonemptyCompacts.instOrderTopNonemptyCompactsToLEToPreorderToPartialOrderInstSemilatticeSupNonemptyCompacts = OrderTop.lift SetLike.coe ⋯ ⋯
In an inhabited space, the type of nonempty compact subsets is also inhabited, with default element the singleton set containing the default element.
Equations
- TopologicalSpace.NonemptyCompacts.instInhabitedNonemptyCompacts = { default := { toCompacts := { carrier := {default}, isCompact' := ⋯ }, nonempty' := ⋯ } }
Equations
- ⋯ = ⋯
Equations
- ⋯ = ⋯
The product of two TopologicalSpace.NonemptyCompacts
, as a TopologicalSpace.NonemptyCompacts
in the product space.
Equations
- TopologicalSpace.NonemptyCompacts.prod K L = let __src := TopologicalSpace.Compacts.prod K.toCompacts L.toCompacts; { toCompacts := __src, nonempty' := ⋯ }
Instances For
Positive compact sets #
The type of compact sets with nonempty interior of a topological space.
See also TopologicalSpace.Compacts
and TopologicalSpace.NonemptyCompacts
.
- carrier : Set α
- isCompact' : IsCompact self.carrier
- interior_nonempty' : Set.Nonempty (interior self.carrier)
Instances For
Equations
- TopologicalSpace.PositiveCompacts.instSetLikePositiveCompacts = { coe := fun (s : TopologicalSpace.PositiveCompacts α) => s.carrier, coe_injective' := ⋯ }
See Note [custom simps projection].
Equations
Instances For
Reinterpret a positive compact as a nonempty compact.
Equations
- TopologicalSpace.PositiveCompacts.toNonemptyCompacts s = { toCompacts := s.toCompacts, nonempty' := ⋯ }
Instances For
Equations
- One or more equations did not get rendered due to their size.
Equations
- TopologicalSpace.PositiveCompacts.instSemilatticeSupPositiveCompacts = Function.Injective.semilatticeSup SetLike.coe ⋯ ⋯
Equations
- TopologicalSpace.PositiveCompacts.instOrderTopPositiveCompactsToLEToPreorderToPartialOrderInstSemilatticeSupPositiveCompacts = OrderTop.lift SetLike.coe ⋯ ⋯
The image of a positive compact set under a continuous open map.
Equations
- TopologicalSpace.PositiveCompacts.map f hf hf' K = let __src := TopologicalSpace.Compacts.map f hf K.toCompacts; { toCompacts := __src, interior_nonempty' := ⋯ }
Instances For
In a nonempty locally compact space, there exists a compact set with nonempty interior.
Equations
- ⋯ = ⋯
The product of two TopologicalSpace.PositiveCompacts
, as a TopologicalSpace.PositiveCompacts
in the product space.
Equations
- TopologicalSpace.PositiveCompacts.prod K L = { toCompacts := TopologicalSpace.Compacts.prod K.toCompacts L.toCompacts, interior_nonempty' := ⋯ }
Instances For
Compact open sets #
The type of compact open sets of a topological space. This is useful in non Hausdorff contexts, in particular spectral spaces.
Instances For
Equations
- TopologicalSpace.CompactOpens.instSetLikeCompactOpens = { coe := fun (s : TopologicalSpace.CompactOpens α) => s.carrier, coe_injective' := ⋯ }
See Note [custom simps projection].
Equations
Instances For
Reinterpret a compact open as an open.
Equations
- TopologicalSpace.CompactOpens.toOpens s = { carrier := ↑s, is_open' := ⋯ }
Instances For
Reinterpret a compact open as a clopen.
Equations
- TopologicalSpace.CompactOpens.toClopens s = { carrier := ↑s, isClopen' := ⋯ }
Instances For
Equations
- TopologicalSpace.CompactOpens.instSupCompactOpens = { sup := fun (s t : TopologicalSpace.CompactOpens α) => { toCompacts := s.toCompacts ⊔ t.toCompacts, isOpen' := ⋯ } }
Equations
- TopologicalSpace.CompactOpens.instInfCompactOpens = { inf := fun (U V : TopologicalSpace.CompactOpens α) => { toCompacts := { carrier := ↑U ∩ ↑V, isCompact' := ⋯ }, isOpen' := ⋯ } }
Equations
- TopologicalSpace.CompactOpens.instSemilatticeInfCompactOpens = Function.Injective.semilatticeInf SetLike.coe ⋯ ⋯
Equations
- One or more equations did not get rendered due to their size.
Equations
- TopologicalSpace.CompactOpens.instHasComplCompactOpens = { compl := fun (s : TopologicalSpace.CompactOpens α) => { toCompacts := { carrier := (↑s)ᶜ, isCompact' := ⋯ }, isOpen' := ⋯ } }
Equations
- TopologicalSpace.CompactOpens.instSemilatticeSupCompactOpens = Function.Injective.semilatticeSup SetLike.coe ⋯ ⋯
Equations
- TopologicalSpace.CompactOpens.instOrderBotCompactOpensToLEToPreorderToPartialOrderInstSemilatticeSupCompactOpens = OrderBot.lift SetLike.coe ⋯ ⋯
Equations
- TopologicalSpace.CompactOpens.instGeneralizedBooleanAlgebraCompactOpens = Function.Injective.generalizedBooleanAlgebra SetLike.coe ⋯ ⋯ ⋯ ⋯ ⋯
Equations
- TopologicalSpace.CompactOpens.instBoundedOrderCompactOpensToLEToPreorderToPartialOrderInstSemilatticeSupCompactOpens = BoundedOrder.lift SetLike.coe ⋯ ⋯ ⋯
Equations
- TopologicalSpace.CompactOpens.instBooleanAlgebraCompactOpens = Function.Injective.booleanAlgebra SetLike.coe ⋯ ⋯ ⋯ ⋯ ⋯ ⋯ ⋯
The image of a compact open under a continuous open map.
Equations
- TopologicalSpace.CompactOpens.map f hf hf' s = { toCompacts := TopologicalSpace.Compacts.map f hf s.toCompacts, isOpen' := ⋯ }
Instances For
The product of two TopologicalSpace.CompactOpens
, as a TopologicalSpace.CompactOpens
in the
product space.
Equations
- TopologicalSpace.CompactOpens.prod K L = let __src := TopologicalSpace.Compacts.prod K.toCompacts L.toCompacts; { toCompacts := __src, isOpen' := ⋯ }