International Journal of Mathematics and Mathematical Sciences
Volume 20 (1997), Issue 3, Pages 423-432
doi:10.1155/S0161171297000586
On the inverse image of Baire spaces
Mustafa Çiçek
Department of Mathematics, Faculty of Science, Ankara University, Beşvler, Ankara 06100, Turkey
Abstract
In 1961, Z. Frolik proved that if f is an open and continuous mapping of a metrizable separable space X onto Baire space Y and if the point inverses are Baire spaces, then X is a Baire space. We give a generalization to semi-continuous and semi-open mapping of this theorem and extended it to the several types of mappings.