Consider the random bipartite graph with vertex classes of size $n$ and each edge being present independently with probability $p(n)$.
I know one way to prove the threshold of a perfect matching is to look at Halls theorem, but could we do it using first and second moment methods?
To clarify what I mean. We can work out using Halls theorem a value for the probability $p$ that the graph contains a perfect matching by showing w.h.p $|N(S)|\geq S$ for all subsets $S \subseteq V$.
Can we do the same thing but just by counting sets of independent edges of size $n$ (here both vertex classes have size $n$)? So what I mean here is if I counted all possible sets of $n$ independent edges, and then let $X$ be the random variable representing the number of sets of $n$ independent edges present. Could I obtain this value of $p$ by working out what it needs to be to ensure $X>0$ using first and second moment methods?