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On group uniformities on the square of a space and extending pseudometrics

Published online by Cambridge University Press:  17 April 2009

Michael G. Tkačnko
Affiliation:
Departamento de MatemáticasUniversidad Autonóma, MetropolitanaUnidad IztapalapaMexico 13 e-mail: mich@xanum.uam.mx
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Abstract

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We give some conditions under which, for a given pair (d1, d2) of continuous pseudometrics respectively on X and X3, there exists a continuous semi-norm N on the free topological group F(X) such that N(x · y−1) = d1(x, y) and N(x · y · t−1 · z−1) ≥ d2((x, y), (z, t)) for all x, y, z, tX. The “extension” results are applied to characterise thin subsets of free topological groups and obtain some relationships between natural uniformities on X2 and those induced by the group uniformities *V, V* and *V* of F(X).

Type
Research Article
Copyright
Copyright © Australian Mathematical Society 1995

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