I am a Ritt assistant professor (postdoc) at Columbia University, and also a June Huh visiting fellow at the Center for Mathematical Challenges in KIAS. My field of interest is algebraic geometry.

I often write my name as Yoonjoo Kim without a dash.

From Fall 2022 to Spring 2023, I was a postdoc at Universität Bonn in Daniel Huybrechts' group (ERC HyperK team).

Before that, I was a PhD student at Stony Brook University. My advisor was Radu Laza.

Email: yk3029 [AT] columbia [DOT] edu.

• Abelian fibrations (degeneration of abelian varieties). These include Lagrangian fibrations, Hitchin fibrations, and abelian fibrations of Calabi-Yau varieties. Related keywords are:
  • Néron models, group scheme actions, and δ-regularity
  • Hodge structures and Ngô support theorem
  • Dual abelian fibrations and Fourier-Mukai transforms
• Global geometry and topology of symplectic varieties. These include abelian varieties, compact hyper-Kähler manifolds, and primitive/irreducible symplectic varieties. Related keywords are:
  • Global constructions of symplectic varieties
  • Mumford-Tate and Looijenga-Lunts-Verbitsky groups
  • Chow motives

• A conjectural bound on the second Betti number for hyper-Kähler manifolds (with  R. Laza), Bull. Soc. Math. France (2020).
• The LLV decomposition of hyper-Kähler cohomology (with  M. Green,  R. Laza,  and  C. Robles), Math. Ann. (2022).
• The dual Lagrangian fibration of known hyper-Kähler manifolds, Alg. Geom. (2025).
• Isotrivial Lagrangian fibrations of compact hyper-Kähler manifolds (with  R. Laza  and  O. Martin), submitted.
• The Néron model of a higher-dimensional Lagrangian fibration, submitted.

• AMS Fall 2020 Southeast meeting, October 2020.
• Stony Brook University, November 2020.
• University of Connecticut, February 2021.
• KIAS, Korea, February 2021.
• Michigan State University, September 2021.
• IBS CCG, Korea, September 2021.
• UC Santa Barbara, October 2021.
• University of Massachusetts Amherst, October 2021.
• Institut de Mathématiques de Jussieu, October 2021.
• University of Michigan, November 2021.
• Derived seminar, December 2021.
• University of Georgia, January 2022.
• Yale University, February 2022.
• Seoul National University, August 2022.
• Universität Bonn, October 2022.
• IST Austria, November 2022.
• IBS CCG, Korea, February 2023.
• KIAS, Korea, February 2023.
• KdV University of Amsterdam, March 2023.
• University of Lille, March 2023.
• Western Hemisphere Virtual Symplectic Seminar, April 2023.
• Columbia University, September 2023.
• Stony Brook University, September 2023.
• IBS CCG, Korea, February 2024.
• Princeton University, March 2024.
• Johns Hopkins University, March 2024.
• KIAS, Korea, June 2024.
• Fordham University, September 2024.
• Harvard-MIT, February 2025.
• University of Sheffield, February 2025.
• University of Pennsylvania, February 2025.
• IBS CCG, Korea, March 2025.
• Yonsei University, Korea, March 2025.
• HCMC, Korea, June 2025.
• Stony Brook University, September 2025.

• 2024 Spring. AG learning seminar: Decomposition of the diagonal.
• 2025 Spring. AG learning seminar: P = W conjecture.

• 2024 Fall. Columbia AG seminar.
• 2025 Spring. Columbia AG seminar.
• 2025 Fall. Columbia AG seminar.

• Here is my dissertation: pdf.
  It summarizes some of my work on hyper-Kähler manifolds. It also provides a very brief survey on basic theory of Lagrangian fibered hyper-Kähler manifolds.