Headshot of me

Garrett Ervin

In 2026, I joined the Borel Combinatorics and Complexity research group as a Momentum MSCA Postdoctoral Fellow at the Institute of Mathematics at ELTE in Budapest. My research interests are in set theory, order theory, and combinatorics. Much of my work concerns the structural arithmetic of linear orders. Previously, I was a postdoc at Caltech under Alekos Kechris; before that, I was a postdoc in the math department at Carnegie Mellon under Clinton Conley. I did my doctoral work at UC Irvine under Martin Zeman. You can find my CV here.

As an instructor, I've taught upper division courses in logic, set theory, model theory, and computability theory, and introductory courses on proofs and proof writing, linear algebra, and calculus. I'm currently teaching a course on the arithmetic of linear orders and one-dimensional dynamics (at ELTE). I authored the complete course content for a course on set theory and forcing in the spring of 2024 (at Caltech), as well as a topics course Linear Orders in the fall of 2022 (at Caltech), and a new course Linear Algebra for Data Science in the fall of 2021 (at CMU). Here is a teaching sample from my time at CMU.

Papers and preprints

  1. (with Eric Paul) The additive arithmetic of linear orders (preprint)
    • Here is an old version of the paper, that takes a different approach.
    • Eric has formalized some of our work in Lean!
  2. (with Alvaro Diaz Ramos and Saharon Shelah) Generalized sums of linear orders (preprint)
  3. (with Alberto Marcone and Thilo Weinert) Untranscendable order types (preprint)
  4. Maximum flows in networks of {0,1}-valued infinitary submodular functions (preprint)
  5. Self-embeddings of linear orders (preprint)
  6. (with Ethan Gu) Left absorption in products of countable orders (Order (Dec. 17, 2024): 1-25)
  7. Decomposing the real line into everywhere isomorphic suborders (Proceedings of the AMS: 152.03 (2024): 925-939)
  8. Distinct orders dividing each other on both sides (Proceedings of the AMS 147 (2019): 3729-3741)
  9. Every linear order isomorphic to its cube is isomorphic to its square (Advances in Mathematics 313 (2017): 237-281)

In progress

  1. (with Eric Paul) Cancellation and absorption in products of linear orders

Linear orders sketchbook

My thesis

Selected Slides

  1. Euclidean division and commutativity
  2. New arithmetic laws for order types
  3. A dichotomy theorem for order types of orbit equivalence relations on R
  4. Arithmetic of linear orders
  5. Infinitary submodular functions and filter flows
  6. Filter flows
  7. Self-similar structures
  8. The cube problem for linear orders

Current teaching at ELTE

  1. The arithmetic of linear orders and one-dimensional dynamics Fall, 2026

Past Teaching at Caltech

  1. Intro to Logic Spring, 2025
  2. Computability Theory II Winter, 2025
  3. Computability Theory I Fall, 2024
  4. Set Theory II Spring, 2024
  5. Set Theory I Winter, 2024
  6. Model Theory Fall, 2023
  7. Computability Theory III Spring, 2023
  8. Computability Theory II Winter, 2023
  9. Linear Orders Fall, 2022

Past Teaching at CMU

  1. Concepts of Mathematics Spring, 2022
  2. Linear Algebra For Data Science Fall, 2021
  3. Concepts of Mathematics Spring, 2021
  4. Integration and Approximation Fall, 2020
  5. Concepts of Mathematics Summer II, 2020
  6. Concepts of Mathematics Spring, 2020
  7. Integration and Approximation Fall, 2019
  8. Concepts of Mathematics Spring, 2019
  9. Basic Logic Fall, 2018
  10. Concepts of Mathematics Summer II, 2018