\begin{definition}[Definition:Sequential Continuity/Domain]
Let $T_1 = \struct {S_1, \tau_1}$ and $T_2 = \struct {S_2, \tau_2}$ be topological spaces.
Let $f: S_1 \to S_2$ be a mapping.
$f$ is '''sequentially continuous on $T_1$''' {{iff}} $f$ is sequentially continuous at $x$ for every $x \in T_1$.
\end{definition}