We provide necessary and/or sufficient conditions on vector spaces $V$ of real sequences to be a Fr\'{ e}chet space such that each coordinate map is continuous, that is, to be a locally convex FK space. In particular, we show that if $c_{ 00}(\mathcal{ I})\subseteq V\subseteq \ell_\infty(\mathcal{ I})$ for some ideal $\mathcal{ I}$ on $\omega$, then $V$ is a locally convex FK space if and only if there exists an infinite set $S\subseteq \omega$ for which every infinite subset does not belong to $\mathcal{ I}$.
Categories: math.FA math.GN