On local non-compactness in recursive mathematics

نویسنده

  • Jakob Grue Simonsen
چکیده

A metric space is said to be locally non-compact if every neighborhood contains a sequence that is bounded away from every element of the space, hence contains no accumulation point. We show within recursive mathematics that a nonvoid complete metric space is locally non-compact iff it is without isolated points. The result has an interesting consequence in computable analysis: If a complete metric space has a computable witness that it is without isolated points, then every neighborhood contains a computable sequence that is eventually computably bounded away from every computable element of the space.

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عنوان ژورنال:
  • Math. Log. Q.

دوره 52  شماره 

صفحات  -

تاریخ انتشار 2006