Weak dual topology #
We continue in the setting of Mathlib/Topology/Algebra/Module/WeakBilin.lean,
which defines the weak topology given two vector spaces E and F over a commutative semiring
š and a bilinear form B : E āā[š] F āā[š] š. The weak topology on E is the coarsest topology
such that for all y : F every map fun x => B x y is continuous.
In this file, we consider two special cases.
In the case that F = E āL[š] š and B being the canonical pairing, we obtain the weak-*
topology, WeakDual š E := (E āL[š] š). Interchanging the arguments in the bilinear form yields the
weak topology WeakSpace š E := E.
Main definitions #
The main definitions are the types WeakDual š E and WeakSpace š E,
with the respective topology instances on it.
WeakDual š Eis a type synonym forDual š E(when the latter is defined): both are equal to the typeE āL[š] šof continuous linear maps from a moduleEoveršto the ringš.- The instance
WeakDual.instTopologicalSpaceis the weak-* topology onWeakDual š E, i.e., the coarsest topology making the evaluation maps at allz : Econtinuous. WeakSpace š Eis a type synonym forE(when the latter is defined).- The instance
WeakSpace.instTopologicalSpaceis the weak topology onE, i.e., the coarsest topology such that allv : dual š Eremain continuous.
References #
Tags #
weak-star, weak dual, duality
The weak star topology is the topology coarsest topology on E āL[š] š such that all
functionals fun v => v x are continuous.
Equations
- WeakDual š E = WeakBilin (topDualPairing š E)
Instances For
Equations
- instTopologicalSpaceWeakDual š E = { IsOpen := instTopologicalSpaceWeakDual._aux_1 š E, isOpen_univ := āÆ, isOpen_inter := āÆ, isOpen_sUnion := ⯠}
Equations
- instInhabitedWeakDual š E = { default := instInhabitedWeakDual._aux_1 š E }
Equations
- instFunLikeWeakDual š E = { coe := instFunLikeWeakDual._aux_1 š E, coe_injective := ⯠}
If a monoid M distributively continuously acts on š and this action commutes with
multiplication on š, then it acts on WeakDual š E.
Equations
- WeakDual.instMulAction M = { smul := WeakDual.instMulAction._aux_1 M, mul_smul := āÆ, one_smul := ⯠}
Equations
- One or more equations did not get rendered due to their size.
If a monoid M distributively continuously acts on š and this action commutes with
multiplication on š, then it acts distributively on WeakDual š E.
Equations
- WeakDual.instDistribMulAction M = { toMulAction := WeakDual.instMulAction M, smul_zero := āÆ, smul_add := ⯠}
If a monoid M distributively continuously acts on š and this action commutes with
multiplication on š, then it continuously acts on WeakDual š E.
If š is a topological module over a semiring R and scalar multiplication commutes with the
multiplication on š, then WeakDual š E is a module over R.
Equations
- WeakDual.instModule' R = { toDistribMulAction := WeakDual.instDistribMulAction R, add_smul := āÆ, zero_smul := ⯠}
Equations
For vector spaces E, there is a canonical map StrongDual š E ā WeakDual š E (the "identity"
mapping). It is a linear equivalence.
Equations
- StrongDual.toWeakDual = LinearEquiv.refl š (StrongDual š E)
Instances For
For vector spaces E, there is a canonical map WeakDual š E ā StrongDual š E (the "identity"
mapping). It is a linear equivalence. Here it is implemented as the inverse of the linear
equivalence StrongDual.toWeakDual in the other direction.
Equations
Instances For
Equations
- One or more equations did not get rendered due to their size.
The weak topology is the topology coarsest topology on E such that all functionals
fun x => v x are continuous.
Equations
- WeakSpace š E = WeakBilin (topDualPairing š E).flip
Instances For
Equations
- instTopologicalSpaceWeakSpace š E = { IsOpen := instTopologicalSpaceWeakSpace._aux_1 š E, isOpen_univ := āÆ, isOpen_inter := āÆ, isOpen_sUnion := ⯠}
Equations
- One or more equations did not get rendered due to their size.
Equations
- WeakSpace.instModule' = { toSMul := instSMulWeakSpaceOfModule, mul_smul := āÆ, one_smul := āÆ, smul_zero := āÆ, smul_add := āÆ, add_smul := āÆ, zero_smul := ⯠}
Equations
A continuous linear map from E to F is still continuous when E and F are equipped with
their weak topologies.
Equations
- WeakSpace.map f = { toLinearMap := āf, cont := ⯠}
Instances For
There is a canonical map E ā WeakSpace š E (the "identity"
mapping). It is a linear equivalence.
Equations
- toWeakSpace š E = LinearEquiv.refl š E
Instances For
For a topological vector space E, "identity mapping" E ā WeakSpace š E is continuous.
This definition implements it as a continuous linear map.
Equations
- toWeakSpaceCLM š E = { toLinearMap := ā(toWeakSpace š E), cont := ⯠}
Instances For
The canonical map from WeakSpace š E to E is an open map.
A set in E which is open in the weak topology is open.
Equations
- One or more equations did not get rendered due to their size.