Rami Grossberg

Rami Grossberg is a full professor of mathematics at Carnegie Mellon University and works in model theory.

Grossberg's work in the past few years has revolved around the classification theory of non-elementary classes. In particular, he has provided, in joint work with Monica VanDieren, a proof of an upward "Morley's Categoricity Theorem" (a version of Shelah's categoricity conjecture) for Abstract Elementary Classes with the amalgamation property, that are tame. In another work with VanDieren, they also initiated the study of tame Abstract Elementary Classes. Tameness is both a crucial technical property in categoricity transfer proofs and an independent notion of interest in the area – it has been studied by Baldwin, Hyttinen, Lessmann, Kesälä, Kolesnikov, Kueker among others. Other results include a best approximation to the main gap conjecture for AECs (with Olivier Lessmann), identifying AECs with JEP, AP, no maximal models and tameness as the uncountable analog to Fraïssé's constructions (with VanDieren), a stability spectrum theorem and the existence of Morley sequences for those classes (also with VanDieren). In addition to this work on the Categoricity Conjecture, more recently, with Boney and Vasey, new understanding of frames in AECs and forking (in the abstract elementary class setting) has been obtained.

Some of Grossberg's work may be understood as part of the big project on Saharon Shelah's outstanding categoricity conjectures:

Conjecture 1. (Categoricity for ${\displaystyle {\mathit {L}}_{{\omega _{1}},\omega }}$). Let ${\displaystyle \psi }$ be a sentence. If ${\displaystyle \psi }$ is categorical in a cardinal ${\displaystyle \;>\beth _{\omega _{1}}}$ then ${\displaystyle \psi }$ is categorical in all cardinals ${\displaystyle \;>\beth _{\omega _{1}}}$. See Infinitary logic and Beth number.

...
Wikipedia