We investigate the invariance of
certain classes of generalized metric spaces under finite-to-one open maps. In
particular, the following classes of spaces are invariant: wΔ− spaces, β-spaces,
Σ#-spaces, wγ-spaces, γ-spaces, quasi-metriza. ble T1-spaces, a-spaces and Moore
spaces. Several applications are given, including a metrization theorem via
finite-to-one open maps. We also show that M-spaces, wM-spaces, wN-spaces, and
Mi-spaces (i = 1,2,3) are not necessarily preserved by finite-to-one open maps.
Further, an example is presented which shows that some of those classes of space
which are invariant under finite-to-one open maps are not necessarily invariant under
compact open maps.
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