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A moderate uniform structure $\mathcal U$ on $\Bbb R$ is one for which

  1. $\forall U\in \mathcal U, \exists n\in \Bbb N,\quad U^n=\Bbb R^2$ but
  2. $ \not\exists n\in \Bbb N,\forall U\in \mathcal U,\quad U^n=\Bbb R^2$

where $U^1=U$, $U^2=U\circ U$, etc.

condition 1 tells us all entourages must be large enough and condition 2 says they must not be too large.

Is there any moderate uniform structure (probably compatible with usual topology) on $\Bbb R$?

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  • $\begingroup$ Not part of question above, but is there a moderate uniform space that is not totally bounded? $\endgroup$ – user35674 Sep 28 '13 at 3:30
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Let $\phi:\mathbb{R} \to (0,1)$ be a homeomorphism. Let $\mathcal{U}$ be the pull-back by $\phi$ of the standard metric uniform structure on $(0,1)$.

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