On normality of the Wijsman topology

Abstract

Let $(X,\rho)$ be a metric space and $(CL(X),W_\rho)$ be the hyperspace of all nonempty closed subsets of $X$ equipped with the Wijsman topology. The Wijsman topology is one of the most important classical hyperspace topologies. We give a partial answer to a question posed in \cite{maio} whether the normality of $(CL(X),W_\rho)$ is equivalent to its metrizability. If $(X,\rho)$ is a linear metric space, then $(CL(X),W_\rho)$ is normal if and only if $(CL(X),W_\rho)$ is metrizable. Some further results concerning normality of the Wijsman topology on $CL(X)$ are also proved.