Topology induced by a family of seminorms #
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Main definitions #
seminorm_family.basis_sets: The set of open seminorm balls for a family of seminorms.seminorm_family.module_filter_basis: A module filter basis formed by the open balls.seminorm.is_bounded: A linear mapf : E →ₗ[𝕜] Fis bounded iff every seminorm inFcan be bounded by a finite number of seminorms inE.
Main statements #
with_seminorms.to_locally_convex_space: A space equipped with a family of seminorms is locally convex.with_seminorms.first_countable: A space is first countable if it's topology is induced by a countable family of seminorms.
Continuity of semilinear maps #
If E and F are topological vector space with the topology induced by a family of seminorms, then
we have a direct method to prove that a linear map is continuous:
seminorm.continuous_from_bounded: A bounded linear mapf : E →ₗ[𝕜] Fis continuous.
If the topology of a space E is induced by a family of seminorms, then we can characterize von
Neumann boundedness in terms of that seminorm family. Together with
linear_map.continuous_of_locally_bounded this gives general criterion for continuity.
with_seminorms.is_vonN_bounded_iff_finset_seminorm_boundedwith_seminorms.is_vonN_bounded_iff_seminorm_boundedwith_seminorms.image_is_vonN_bounded_iff_finset_seminorm_boundedwith_seminorms.image_is_vonN_bounded_iff_seminorm_bounded
Tags #
seminorm, locally convex
An abbreviation for indexed families of seminorms. This is mainly to allow for dot-notation.
The sets of a filter basis for the neighborhood filter of 0.
The add_group_filter_basis induced by the filter basis seminorm_basis_zero.
Equations
- p.add_group_filter_basis = add_group_filter_basis_of_comm p.basis_sets _ _ _ _ _
The module_filter_basis induced by the filter basis seminorm_basis_zero.
Equations
- p.module_filter_basis = {to_add_group_filter_basis := p.add_group_filter_basis _inst_4, smul' := _, smul_left' := _, smul_right' := _}
The proposition that a linear map is bounded between spaces with families of seminorms.
- topology_eq_with_seminorms : t = p.module_filter_basis.topology
The proposition that the topology of E is induced by a family of seminorms p.
The x-neighbourhoods of a space whose topology is induced by a family of seminorms
are exactly the sets which contain seminorm balls around x.
The open sets of a space whose topology is induced by a family of seminorms are exactly the sets which contain seminorm balls around all of their points.
A separating family of seminorms induces a T₁ topology.
A family of seminorms inducing a T₁ topology is separating.
A family of seminorms is separating iff it induces a T₁ topology.
Convergence along filters for with_seminorms.
Variant with finset.sup.
Convergence along filters for with_seminorms.
Limit → ∞ for with_seminorms.
The topology induced by a family of seminorms is exactly the infimum of the ones induced by
each seminorm individually. We express this as a characterization of with_seminorms p.
The uniform structure induced by a family of seminorms is exactly the infimum of the ones
induced by each seminorm individually. We express this as a characterization of
with_seminorms p.
The topology of a normed_space 𝕜 E is induced by the seminorm norm_seminorm 𝕜 E.
Not an instance since 𝕜 can't be inferred. See normed_space.to_locally_convex_space for a
slightly weaker instance version.
See normed_space.to_locally_convex_space' for a slightly stronger version which is not an
instance.
The family of seminorms obtained by composing each seminorm by a linear map.
If the topology of a space is induced by a countable family of seminorms, then the topology is first countable.