The following question I also posed [here] (http://math.stackexchange.com/questions/298104/when-is-a-sequentially-closed-cone-closed), but still got no answer. Let $X$ be a locally convex, Hausdorff topological vector space and $C\subseteq X$ a convex cone, which is sequentially closed. What are criteria, that would imply that $C$ is closed (in the topology of X)?Are there also "testifyable" criteria?