From: Graven Water on
What does it mean for two metrics on a space to be uniformly equivalent?

I found a statement in a book: "all metrics on a compact metrizable space
are uniformly equivalent".

I thought if d and e are two metrics on a space X, d and e are
_uniformly equivalent_ if there are K and M such that
d(x,y) <= K e(x,y) all x,y in X
e(x,y) <= M d(x,y) all x,y in X.

But then the book's statement doesn't seem to be true!

Laura

From: John Coleman on
On Mar 31, 10:22 am, p...(a)grex.org (Graven Water) wrote:
> What does it mean for two metrics on a space to be uniformly equivalent?
>

For every \epsilon > 0 there exists a \delta > 0 such that
d(x,y) < \delta => e(x,y) < \epsilon
e(x,y) < \delta => d(x,y) < \epsilon

> I found a statement in a book:  "all metrics on a compact metrizable space
> are uniformly equivalent".
>
> I thought if  d  and  e  are two metrics on a space  X, d  and  e  are
> _uniformly equivalent_ if there are K and M such that
> d(x,y) <= K e(x,y) all x,y in X
> e(x,y) <= M d(x,y) all x,y in X.

That sounds more like Lipschitz equivalence

> But then the book's statement doesn't seem to be true!  
>
> Laura

From: Graven Water on
OK, I found out the following isn't the actual definition.

Laura

> I thought if d and e are two metrics on a space X, d and e are
> _uniformly equivalent_ if there are K and M such that
> d(x,y) <= K e(x,y) all x,y in X
> e(x,y) <= M d(x,y) all x,y in X.

From: Dave L. Renfro on
Graven Water (Laura?) wrote (in part):

> What does it mean for two metrics on a space to be
> uniformly equivalent?

John Coleman has answered your question already, but
if you're interested in more about this topic, I posted
quite a bit on it back in 2006:

"Lipschitz, uniformly, and topologically equivalent metrics"
sci.math post made on 4 October 2006
http://groups.google.com/group/sci.math/msg/9e825cd2be094cd7

Dave L. Renfro