Notes on closed mappings

• Autores: Chuan Liu
• Localización: Houston journal of mathematics, ISSN 0362-1588, Vol. 33, Nº 1, 2007, págs. 249-259
• Idioma: inglés
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• Resumen

  • In this paper, we characterize closed sigma-compact images of metric spaces as Fr\'echet, weakly quasi-first-countable spaces with a sigma-locally finite k-network; and discuss the fibers of closed mappings on some generalized metric spaces and improve some Tanaka's results and answered a Yun's question. It is also shown that g-metrizable spaces and spaces with a point-countable base are preserved by closed sequence-covering mappings, which gives an affirmative answer to a Lin's question.