English

The reals as rational Cauchy filters

History and Overview 2015-11-06 v3

Abstract

We present a detailed and elementary construction of the real numbers from the rational numbers a la Bourbaki. The real numbers are defined to be the set of all minimal Cauchy filters in Q\mathbb{Q} (where the Cauchy condition is defined in terms of the absolute value function on Q\mathbb{Q}) and are proven directly, without employing any of the techniques of uniform spaces, to form a complete ordered field. The construction can be seen as a variant of Bachmann's construction by means of nested rational intervals, allowing for a canonical choice of representatives.

Keywords

Cite

@article{arxiv.1503.04348,
  title  = {The reals as rational Cauchy filters},
  author = {Ittay Weiss},
  journal= {arXiv preprint arXiv:1503.04348},
  year   = {2015}
}
R2 v1 2026-06-22T08:53:08.614Z