EDB — 0KV

[0KV]Prerequisites:[0J1]↺↻.Let $X=\{1,2,3\}$ and let $\mathcal{B}=\{\{1,2\},\{2,3\}\}$; let $𝜏$ be the smallest topology that contains $\mathcal{B}$, show that $\mathcal{B}$ is not a base for $𝜏$.

It is therefore interesting to try to understand when a family $\mathcal{B}$ can be the base for a topology.