Definition

A local field is a nondiscrete Hausdorff topological field whose underlying space is .

Under this convention, the local fields are the R\mathbb R and C\mathbb C, together with the .

Convention warning

Some authors reserve “local field” for the nonarchimedean cases. Statements in harmonic analysis and the Langlands program should therefore say “archimedean” or “nonarchimedean” whenever the distinction affects the objects under discussion.

Relation to global fields

The FvF_v of a at a place is a local field. Conversely, every local field arises as such a completion, though not canonically from a unique global field.

References
  1. André Weil, Basic Number Theory, third edition, Springer, 1974, Chapter I.
  2. Jean-Pierre Serre, Local Fields, Springer, 1979, Chapter I.