Skip to main content
4 of 4
added 67 characters in body
Anton Petrunin
  • 45k
  • 14
  • 135
  • 299

Proper space is the a complete space such that any bounded subset is totally bounded,

  • or equivalently, in which any bounded sequence contains a converging subsequence,
  • or equivalently, any bounded closed set is compact,
  • or equivalently, the distance function from one (and therefore any) point is proper; the latter means that invese image of any compact set is compact.

For noncomplete space you may say space with proper completion, or you may call it preproper space by analogy with precompact.

Anton Petrunin
  • 45k
  • 14
  • 135
  • 299