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Anton Petrunin
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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.

Anton Petrunin
  • 45k
  • 14
  • 135
  • 299