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14 votes
1 answer
500 views

Is there an 'unnatural' topological construction of an algebraically closed field of positive characteristic?

It's well known that while there is a natural topological construction of a nearly algebraically closed field of characteristic $0$, algebraically closed fields of positive characteristic seemingly ...
James E Hanson's user avatar
12 votes
1 answer
898 views

Converse to Banach’s fixed point theorem for ordered fields?

Suppose $R$ is an ordered field. Call a continuous map $f: R \rightarrow R$ a contraction if there exists $r < 1$ (in $R$) such that $|f(x)-f(y)| \leq r |x-y|$ for all $x,y \in R$ (where $|x| := \...
James Propp's user avatar
  • 19.7k
1 vote
0 answers
70 views

Given a topological field with non-trivial topology given by a metric, is the metric necessarily translation-invariant? [closed]

If the topology is locally compact and non-trivial, then the metric is usually translation-invariant or even arises from a norm. But is it necessary to be invariant? I failed to give a counterexample.
wuzx's user avatar
  • 517
1 vote
0 answers
187 views

How to prove that $k(x)$ is not complete in the $x$-adic metric [closed]

It is not hard to find proofs showing that $\mathbb{Q}$ is not complete with respect to the metric induced by the valuation $|\;\;|_p$. For example, it is enough to recall that every complete metric ...
Chilote's user avatar
  • 596