A Probability of Topology: The probability of a uniformly sampled subset of the powerset being a topology on that set

29 Views Asked by At

Let's say we have a finite set $S$ where $|S|=n$ and we take its powerset $X = \mathcal{P}(S)$ to generate a measurable space $(X, \mathcal{P}(X))$. From this we consider the probability space $(X, \mathcal{P}(X), \mathbb{P})$ where $\mathbb{P}$ is a uniform probability measure. What is the probability that a uniformly sampled $A \in \mathcal{P}(X)$ is a topology on S?

My intuition is that the probability will vanish as $n \rightarrow \infty$, but for finite sets it should be non-zero since there exists members of $\mathcal{P}(X)$ that are topologies on $S$.