Strongly Pseudoradial Spaces

Abstract

The "weakly Hausdorff" property for pseudoradial spaces fails to be naturally characterized by unique convergence of transfinite sequences. In response, we develop the category $\mathbf{SPsRad}$ of strongly pseudoradial spaces, compactly generated spaces whose closed sets are determined by globally continuous maps from well-ordered spaces. Categorically, $\mathbf{SPsRad}$ is the coreflective hull of the class of well-ordered spaces, and $\mathbf{SPsRad}$ is Cartesian closed. The strongly pseudoradial weakly Hausdorff spaces admit a natural characterization involving unique extensions of injective maps of well-ordered spaces. We also obtain analogs in $\mathbf{SPsRad}$ of the fact that for sequential spaces, sequential compactness is equivalent to countable compactness.