indiscernible sequence?
Morley sequence?
Ramsey theorem?
Erdos-Rado theorem?
Ehrenfeucht-Fraïssé games (back-and-forth games)
Hrushovski construction?
generic predicate?
Ultracategories are categories with extra structure, called an ultrastructure (see Lurie, Sec 1.3). They were introduced in Makkai 87 in order to prove conceptual completeness, but note that Lurie’s definition differs from Makkai’s (Lurie, Warning 1.0.4).
Mihaly Makkai, Stone duality for first-order logic, Adv. Math. 65 (1987) no. 2, 97–170, doi, MR89h:03067
Jacob Lurie, Ultracategories, (pdf)
Last revised on January 8, 2019 at 09:03:18. See the history of this page for a list of all contributions to it.