Tagged Questions

2
votes
1answer
99 views

Tensor product of C*-algebras of bounded, uniformly continuous functions on metric spaces

This is a follow up question to this one. If $X$ is a metric space, denote by $C_u(X)$ the $C^\ast$-algebra of all bounded, uniformly continuous functions on $X$ (with the sup-nor …
2
votes
1answer
57 views

Extending uniformly continuous functions on subspaces to non-metrizable compactifications

I have a complete metric space $Y$, some non-metrizable(!) Hausdorff compactification $Z$ of it and a subspace $X \subset Y$. Furthermore, I do have a uniformly continuous functio …
3
votes
2answers
144 views

For any entourage $U,V$ there’s an entourage $W$ such that $U\circ W\subseteq V\circ U$

Let $(X,\mathcal U)$ be a uniform space and let $U\in \mathcal U$. Is this statement true? $$\forall V\in \mathcal U, \exists W\in \mathcal U, U\circ W\subseteq V\circ U$$ I think …
-2
votes
0answers
115 views

Is the topology generated by $\lbrace D[a] \mid a \in F \rbrace$ completely regular?

Suppose $(X,\mathcal D)$ is a precompact uniform space and $D\in \mathcal D$. there's a finite set $F\subseteq X$ such that $$D[F]=X$$ Let $\mathcal T$ be the topology on $X$ gener …
1
vote
1answer
105 views

A uniformity with a countable base is a pseudometric uniformity.

I need a proof for this proposition: If a uniformity $\mathfrak U$ on $X$ has a countable fundamental system of entourages, then it can be defined by a pseudometric on $X …
3
votes
1answer
167 views

Does every proximal outer measure, measure all open sets?

Let $\: \langle X,\hspace{-0.015 in}\delta\hspace{.005 in}\rangle \:$ be a separated proximity space. Let $\;\;\; \mu^* \: : \: 2^{\hspace{.01 in}X} \: \to \: \left[0,\hspace{-0.0 …
10
votes
2answers
274 views

Start with a topological group, take the meet of the two uniformities, and take the topology. Is the result again a topological group? [xpost from math.SE]

And what else can be said, if so? (Original math.SE post) In more detail: Say $(G,\mathscr{T})$ is a topological group. It has a left uniformity $\mathscr{L}$ and a right uniform …
1
vote
0answers
71 views

Collapse a closed subset of a uniform space.

I have proved that if you collapse a closed subset of a separated (Hausdorff) uniform space to a point, you get a separated uniform space. Surely such a simple result must be stan …
3
votes
3answers
316 views

Does every Lindelof uniform space have a Lindelof completion?

Recall Lindelof = every open cover has a countable subcover. Is the question of the title answered by known material from some standard text on uniform spaces? Note it is well kn …
6
votes
4answers
790 views

Finite dimensional vector spaces over a complete but not-necessarily-valued field

I'm essentially reopening this old question of Ricky Demer which was never fully answered. Essentially the original question: Suppose we have a topological field $F$ which is comp …
4
votes
1answer
212 views

Does the weak approximation theorem hold for general topological fields?

The weak approximation theorem states that given a field $F$ and nontrivial inequivalent absolute values $|\cdot|_1,\ldots,|\cdot|_n,$ and letting $F_i$ denote $F$ with the topolog …
2
votes
1answer
229 views

Chaos in uniform spaces

Let Dom be a uniform space, and f be a continuous function from Dom to itself satisfying: (1)For all non-empty open subsets U and V of Dom, there exists a natural number n and a m …