An example of a new simple theory

2018/04/09 by Malliaris, M., Shelah, S.
#FOS: Mathematics #Logic (math.LO)

paper · doi:10.48550/arxiv.1804.03254

Abstract

We construct a countable simple theory which, in Keisler's order, is strictly above the random graph (but "barely so") and also in some sense orthogonal to the building blocks of the recently discovered infinite descending chain. As a result we prove in ZFC that there are incomparable classes in Keisler's order.

Related

• Some simple theories from a Boolean algebra point of view
• Keisler's order has infinitely many classes
• Keisler's order is not simple (and simple theories may not be either)
• Low is a Dividing Line in Keisler's Order
• Random graphs in the monadic theory of order