Communications of the
Korean Mathematical Society CKMS

We give two sufficient conditions that the space $(X,c_{\ast})$ be a Fr\' echet-Urysohn space such that $x_{n}\rightarrow x$ in $(X,c)$ if and only if $x_{n}\rightarrow x$ in $(X,c_{\ast})$, where $c_{\ast}$ is the sequential closure operator on a generalized topological space $(X,c)$.

Keywords: semi-closure spaces, sequential closure operators, and Frechet-Urysohn spaces

MSC numbers: 54A05, 54A20, and 54D99