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10 votes
1 answer
561 views

Does a compact contractible metric space have a point that is fixed by all isometries?

Let $(X,d)$ be a compact and contractible metric space. Let $\operatorname{Isom}(X)=\{\phi\colon X\to X\}$ be its group of isometries. Question: Is there a point $x\in X$ fixed by all $\phi\in\...
M. Winter's user avatar
  • 13.6k
6 votes
0 answers
813 views

Limit of metric spaces

Let $\{X_n\}_{n\in \mathbb{N}}$ be a collection of T2 topological spaces, with maps $f_n\colon X_n \to X_{n+1}$. These maps are continuous and open. Let $X$ be the direct limit of this system. Assume ...
Giulio's user avatar
  • 2,384
3 votes
1 answer
244 views

Partitioning a smooth manifold into geodesically convex sets

Let $X$ be a connected and compact $d$-dimensional smooth manifold; where $d$ is a positive integer. Does (or rather, when does) there exist a metric $\rho$ on $X$ generating $X$'s topology and a ...
ABIM's user avatar
  • 5,405
3 votes
0 answers
177 views

When do Polish spaces admit complete metric making them $\mathrm{CAT}(\kappa)$?

Question $\DeclareMathOperator\CAT{CAT}$Let $X$ be a Polish space. When are there known conditions under which $X$'s topology can be metrized by a metric $d$ such that $(X,d)$ is a: $\CAT(\kappa)$ ...
Carlos_Petterson's user avatar
0 votes
1 answer
515 views

Distance between two points using triangulation

Suppose we have two points $p_1$ and $p_2$ in a metric space with unknown dimensionality, with no way to directly compute the distance between them, e.g. no coordinates. Say we can randomly sample a ...
CambridgeStudent's user avatar
0 votes
0 answers
169 views

Do all manifolds admit metrics with Euclidean balls?

Let $M$ be a compact topological n-manifold. Suppose we are given a locally flat embedding $M \subset \mathbb{R}^{n+k}$. This induces a metric on $M$ by restriction. Is it true that for $\epsilon$ ...
Connor Malin's user avatar
  • 5,849