Gregory Johnson is an Associate Teaching Professor in the Department of Mathematical Sciences at Carnegie Mellon University. He holds a Ph.D. from the University of Maryland. His primary responsibilities involve teaching introductory mathematics courses, including calculus and differential equations. His teaching extends to higher-level courses, emphasizing abstract algebra, number theory, set theory, and mathematical logic. His main research focus is on mathematical logic, specifically model theory with an emphasis on abstract elementary classes. Additionally, he has a keen interest in algebraic number theory and is passionate about guiding undergraduate students in research. Notably, he has supervised student projects aimed at extending Giuga's conjecture concerning rings of algebraic integers.