The unitization (over R) of C₀(X, R) is C(OnePoint X, R) #
Given a topological space X and a topological ring R one can extend an element C₀(X, R), the
continuous functions vanishing at infinity, to C(OnePoint X, R), the continuous functions on the
one-point compactification of X, by taking the value 0 at ∞. This can be lifted to an
equivalence between Unitization R C₀(X, R) and C(OnePoint X, R).
Main definitions #
ZeroAtInftyContinuousMap.toOnePoint : C₀(X, R) → C(OnePoint X, R): the extension off : C₀(X, R)to the function which takes the value0at∞ContinuousMap.toZeroAtInfty: C(OnePoint X, R) → C₀(X, R):f ↦ fun x ↦ g x - g ∞
ZeroAtInftyContinuousMap.unitizationEquiv : Unitization R C₀(X, R) ≃ C(OnePoint X, R): liftZeroAtInftyContinuousMap.toOnePointto an equivalence from theUnitization, with inverse given byf ↦ .mk (f ∞, f.toZeroAtInfty)- Various bundled versions of all of the above.
Implementation notes #
The simp normal form of each bundled morphism is the unbundled map, so the unbundled maps have their own simp lemmas for various operatoins.
Extension by zero of a continuous function vanishing at infinity, as a continuous function on the one-point compactification.
Equations
Instances For
ZeroAtInftyContinuousMap.toOnePoint as an AddMonoidHom.
Equations
- ZeroAtInftyContinuousMap.toOnePointAddMonoidHom X R = { toFun := ZeroAtInftyContinuousMap.toOnePoint, map_zero' := ⋯, map_add' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.toOnePoint as a LinearMap.
Equations
- ZeroAtInftyContinuousMap.toOnePointLinearMap X R S = { toFun := ZeroAtInftyContinuousMap.toOnePoint, map_add' := ⋯, map_smul' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.toOnePoint as a NonUnitalRingHom.
Equations
- ZeroAtInftyContinuousMap.toOnePointNonUnitalRingHom X R = { toFun := ZeroAtInftyContinuousMap.toOnePoint, map_mul' := ⋯, map_zero' := ⋯, map_add' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.toOnePoint as a NonUnitalAlgHom.
Equations
- ZeroAtInftyContinuousMap.toOnePointNonUnitalAlgHom X R S = { toFun := ZeroAtInftyContinuousMap.toOnePoint, map_smul' := ⋯, map_zero' := ⋯, map_add' := ⋯, map_mul' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.toOnePoint as a NonUnitalStarAlgHom.
Equations
- ZeroAtInftyContinuousMap.toOnePointNonUnitalStarAlgHom X R S = { toFun := ZeroAtInftyContinuousMap.toOnePoint, map_smul' := ⋯, map_zero' := ⋯, map_add' := ⋯, map_mul' := ⋯, map_star' := ⋯ }
Instances For
The continuous function vanishing at infinity obtained by taking g : C(OnePoint X, R) and
restricting g to X and subtracting the constant g ∞.
Equations
- g.toZeroAtInfty = { toFun := fun (x : X) => g ↑x - g OnePoint.infty, continuous_toFun := ⋯, zero_at_infty' := ⋯ }
Instances For
ContinuousMap.toZeroAtInfty as an AddMonoidHom.
Equations
- ContinuousMap.toZeroAtInftyAddMonoidHom X R = { toFun := ContinuousMap.toZeroAtInfty, map_zero' := ⋯, map_add' := ⋯ }
Instances For
ContinuousMap.toZeroAtInfty as a LinearMap.
Equations
- ContinuousMap.toZeroAtInftyLinearMap X R S = { toFun := ContinuousMap.toZeroAtInfty, map_add' := ⋯, map_smul' := ⋯ }
Instances For
The canonical equivalence Unitization R C₀(X, R) ≃ C(OnePoint X, R) mapping (r, f) to the
function taking the value r at ∞ and r + f x at x : X. Its inverse maps g to
(g ∞, fun x ↦ g x - g ∞). This is the lift of ZeroAtInftyContinuousMap.toOnePoint.
Various bundlings are available including unitizationAddEquiv, unitizationLinearEquiv,
unitizationRingEquiv, unitizationAlgEquiv, unitizationStarAlgEquiv.
Equations
- One or more equations did not get rendered due to their size.
Instances For
ZeroAtInftyContinuousMap.unitizationEquiv as an AddEquiv.
Equations
- ZeroAtInftyContinuousMap.unitizationAddEquiv X R = { toEquiv := ZeroAtInftyContinuousMap.unitizationEquiv X R, map_add' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.unitizationEquiv as a LinearEquiv.
Equations
- One or more equations did not get rendered due to their size.
Instances For
ZeroAtInftyContinuousMap.unitizationEquiv as a RingEquiv.
Equations
- ZeroAtInftyContinuousMap.unitizationRingEquiv X R = { toEquiv := (ZeroAtInftyContinuousMap.unitizationAddEquiv X R).toEquiv, map_mul' := ⋯, map_add' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.unitizationEquiv as an AlgEquiv.
Equations
- ZeroAtInftyContinuousMap.unitizationAlgEquiv X R S = { toEquiv := (ZeroAtInftyContinuousMap.unitizationRingEquiv X R).toEquiv, map_mul' := ⋯, map_add' := ⋯, commutes' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.unitizationEquiv as a StarAlgEquiv.
Equations
- ZeroAtInftyContinuousMap.unitizationStarAlgEquiv X R S = { toRingEquiv := ZeroAtInftyContinuousMap.unitizationRingEquiv X R, map_star' := ⋯, map_smul' := ⋯ }
Instances For
ZeroAtInftyContinuousMap.unitizationStarAlgEquiv is the map obtained lifting
ZeroAtInftyContinuousMap.toOnePoint to the unitization.