<s>[INST] Let \(X\) be a topological space and let \(\mathscr{F}\) be a filter of subsets of \(X\) that has the finite intersection property (that is, every finite subcollection of \(\mathscr{F}\) has a nonempty intersection). Then every neighbourhood \(U\) of an accumulation point of the filter \(\mathscr{F}\) belongs to \(\mathscr{F}\).[/INST]