Definition 8.1.2 (Translation-Invariant Topology). Let $E$ be a vector space and $\topo$ be a topology on $E$, then $\topo$ is translation-invariant if for any $U \in \topo$ and $y \in E$, $U + y \in \topo$.
Definition 8.1.2 (Translation-Invariant Topology). Let $E$ be a vector space and $\topo$ be a topology on $E$, then $\topo$ is translation-invariant if for any $U \in \topo$ and $y \in E$, $U + y \in \topo$.