mathematical terms, nations are highly connected subgraphs of a global network according to one or more network distance metrics, like geographic distance: great circle distance on surface of earth network distance: degrees of separation in a social network genetic distance: eg, Fst (fixation index) or another measure linguistic distance: eg, lexicostatistical measures economic distance: eg, 1 — cosine similarity ideological distance: degree of similarity in belief as expressed by spatial theory of voting The advantage of this definition is that while it’s still fuzzy (how connected exactly does the subgraph have to be?), it’s now amenable to quantitative analysis. Given a network, a set of distance metrics, and some parameter choices, the subgraphs pop out. By this definition, a real nation would have more ingroup than outgroup connections, more “domestic” than “international” calls.
Link:: The Network State