indiscernible sequence? Morley sequence? Ramsey theorem? Erdos-Rado theorem? Ehrenfeucht-Fraïssé games (back-and-forth games) Hrushovski construction? generic predicate? Given a collection of finite(ly-generated) first-order structures which formally resemble collections of finite(ly-generated) substructures found inside an infinite structure, there are additional assumptions on such collections we can make which ensure that they can be amalgamated into an infinite structure which somehow...