$\textbf{Subbasis}$
Let $X$ be a topological space. A set $\frak{S}$ of open sets is called a subbasis for the topology if every open set is a union of finite intersections of sets in $\frak{S}$.
$\textbf{Subbasis}$
Let $X$ be a topological space. A set $\frak{S}$ of open sets is called a subbasis for the topology if every open set is a union of finite intersections of sets in $\frak{S}$.
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𝐒𝐮𝐛𝐛𝐚𝐬𝐢𝐬
Let 𝑋 be a topological space. A set 𝔖 of open sets is called a subbasis for the topology if every open set is a union of finite intersections of sets in 𝔖.