Topology Bases
Definition
A base $\mathcal{B} $ for a topology $\mathcal{T} $ on a set $X$ is a subset of $\mathcal{T} $ such that every open set $U \in \mathcal{T} $ is a union of a family of sets in $\mathcal{B} $.
A base $\mathcal{B} $ for a topology $\mathcal{T} $ on a set $X$ is a subset of $\mathcal{T} $ such that every open set $U \in \mathcal{T} $ is a union of a family of sets in $\mathcal{B} $.