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A metric space is a pair $(X,d)$, where $X$ is a set and $d:X \times X \to \mathbb{R}$ satisfies the following conditions for all $x,y,z \in X$. (Symmetry) $d(x,y)=d(y,x)$. (Identity of Indiscernibles) $d(x,y)=0$ if and only if $x=y$. (Triangle Inequality) $d(x,y)+d(y,z) \geq d(x,z)$.

2 votes
1 answer
112 views

Continuous inclusion of metric spaces of smaller capacity

If $(X,d_X)$ is a compact metric space, and $(Y,d)$ is another metric space. Moreover, suppose that the metric capacity of $(Y,d)$ is at-least that of $(X,d_X)$, that is $$ \kappa_X(\epsilon)\leq \ka …
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1 vote
1 answer
106 views

Continuous Left-inverse of Dirac Lipschitz-Free Space

Let $X$ be a separable pointed metric space and let $AE(X)$ denote the corresponding Lipschitz-Free (or Arens-Eells space) over $X$. The point-evaluation map $\delta:X\mapsto AE(X)$ is injective henc …
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2 votes
2 answers
264 views

Existence of a Hölder-free space

The Lipschitz-free or Arens-Eells space over a pointed separable metric space $(X,0,d)$ is a well-studied object. My question is, is an analogos Hölder-free space; for a fixed Hölder constant $\alpha …
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1 vote
0 answers
84 views

A Hölder version of the Johnson-Lindenstrauss Lemma on essentially bounded functions

Does there exist a Hölder (not necessarily linear) projection from $L^{\infty}(\mathbb{R}^d)$ to any finite-dimensional linear subspace? This is known when $L^{\infty}(\mathbb{R}^d)$ is replaced by a …
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1 vote
1 answer
273 views

Inferring the modulus of continuity

Let $f:X\rightarrow Y$, $g:Y\rightarrow Z$ be uniformly continuous functions between metric spaces $X,Y,Z$ with moduli of continuity $\omega_f$ and $\omega_g$, respectively. Suppose that we know that …
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2 votes
0 answers
221 views

Examples of doubling metric spaces

I keep reading a lot of metric space results which are frames for doubling metric spaces. However, besides some obvious examples (such as Euclidean case, discrete spaces, or quasi-symmetric images of …
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2 votes
1 answer
96 views

Isometry between punctured sphere and punctured triangle?

Setup: Let $C_n$ be a closed $n$-simplex in $\mathbb{R}^n$ and let $r \in (0,R)$ where $R$ is the distance any one of the vertices $\{v_1,\cdots , v_{n+1}\}$ of $C_n$ to the centroid $\frac{v_1+ \c …
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1 vote
0 answers
69 views

Continuous injection of metric ball into Euclidean ball

This is a follow-up to this post. Suppose that $(X,d_X)$ is a compact metric space with (finite) metric-capacity, defined by $$ \kappa_X(\epsilon)\triangleq\sup\left\{ k : \exists x_0,\dots,x_k \i …
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0 votes
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45 views

Skorohod Space with $J_1$ topology homeomorphic to Frechet Space

Is the Skorohod space $D([0,T];\mathbb{R}^d)$ equipped with the $J_1$ topology homoeomorphic to a separable Fr\'{e}chet space. In particular, is it homeomorphic to $L_{\mu}^1(\mathcal{B}([0,1])$ wher …
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0 votes
1 answer
159 views

Restriction of non-metrizable topology to dense subset is non-metrizable

Let $(X,\tau)$ be a non-metrizable topological space which is not first-countable and let $\emptyset \neq Y\subset X$ be a proper dense subset. Is it possible for $(Y,\tau_Y)$ (where $\tau_Y$ is the …
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0 votes
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67 views

Holder-continuous barycenter maps

Let $(X,d)$ be a complete locally-compact metric space. We define the $p$-barycenter map as a continuous function: $$ \beta:\mathcal{P}_p(X)\rightarrow X, $$ which is a right-inverse of the map assoc …
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2 votes
0 answers
101 views

What is the relationship between barycenters in the Arens-Eells sense and barycenters in the...

Setup: Let $X$ be a complete pointed metric space. Let us briefly recall that the Wasserstein space $W_1(X)$ is identifiable with a subset of the Arens-Eells (or Lipschitz-Free) space $\operatorname{A …
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2 votes
1 answer
109 views

Lipschitz maps with Hölder inverse preserve the doubling property

Let $K$ be a compact doubling metric space, $X$ be a metric space and $f:K\rightarrow X$ be Lipschitz with $\alpha$-Hölder inverse, where $0<\alpha<1$. Does $f(K)$ need to be doubling?
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0 votes
0 answers
111 views

Finite sets are residual in the Hausdorff space

Let $X$ be a metric space, let $\mathbb{H}(X)$ denote the set of non-empty closed subsets of $X$ with Hausdorff metric which we denote by $d_{\mathbb{H}(X)}$, and let $\mathbb{H}_{\operatorname{fin}}( …
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1 vote
0 answers
59 views

Explicit Quasisymmetric embedding into Euclidean space

It is known that every doubling metric space admits quasisymmetric map into Euclidean space. My question is, is there a known explicit (closed-form) quasisymmetry from the Heisenberg group into a Euc …
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