Abstract:Let $(E,t)$ be a Hausdorff locally convex space. Either $(E,\sigma (E,E'))$ or \newline $(E',\sigma (E',E))$ is a $DF$-space iff $E$ is of finite dimension (THEOREM). This is the most general solution of the problem studied by Iyahen [2] and Radenovi\v c [3].
Keywords: $DF$-spaces, countably quasibarrelled spaces
AMS Subject Classification: Primary 46A05