The definition of subbasis in Topology I have a question regarding the subbasis; in Munkre's topology, the subbasis is defined in the following picture. But if I take a collection that only contains the set X, can it be a subbasis for a topology on X?

Thanks for your help.

If you take a collection that contains only the set $X$, then clearly union of all the members of that collection will be $X$. So, definitely that collection will be a subbasis and the topology generated by this subbasis is the indiscrete topology which contains only two sets $X$ and the null set $\phi$.
