Every finite system of T1 uniformities comes from a single distance structure

• Heitzig, Jobst ^[1]
  1. [1] Universität Hannover
• Localización: Applied general topology, ISSN-e 1989-4147, ISSN 1576-9402, Vol. 3, Nº. 1, 2002, págs. 65-76
• Idioma: inglés
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• Resumen

  • Using the general notion of distance function introduced in an earlier paper, a construction of the finest distance structure which induces a given quasi-uniformity is given. Moreover, when the usual defining condition xy : d(y; x)  of the basic entourages is generalized to nd(y; x)    n (for a  fixed positive integer n), it turns out that if the value-monoid of the distance function is commutative, one gets a countably infinite family of quasi-uniformities on the underlying set. It is then shown that at least every finite system and every descending sequence of T1 quasi-uniformities which fulfil a weak symmetry condition is included in such a family. This is only possible since, in contrast to real metric spaces, the distance function need not be symmetric.