Cassandra Marcussen

I am a fourth-year Ph.D. student in theoretical computer science at Harvard University, advised by Madhu Sudan. In 2022, I graduated from Columbia University, where I double-majored in Mathematics and Computer Science and was advised by Xi Chen. My research is supported by an NDSEG Fellowship.

I am interested in theoretical computer science and probability theory. I like to think about problems related to sublinear algorithms, random graphs, error correction, and stochastic processes.

My email is cmarcussen-at-g-dot-harvard-dot-edu.

Selected Papers

Quality control in sublinear time: a case study via random graphs [pdf].
with Ronitt Rubinfeld and Madhu Sudan.

A Fast Coloring Oracle for Average Case Hypergraphs [pdf].
with Edward Pyne, Ronitt Rubinfeld, Asaf Shapira, and Shlomo Tauber.
International Conference on Randomization and Computation (RANDOM) 2025.

Beyond Worst Case Local Computation Algorithms [pdf].
with Amartya Shankha Biswas, Ruidi Cao, Edward Pyne, Ronitt Rubinfeld, Asaf Shapira, and Shlomo Tauber.

Characterizing the Distinguishability of Product Distributions through Multicalibration [pdf].
with Aaron (Louie) Putterman and Salil Vadhan.
Computational Complexity Conference (CCC) 2025.

Finding the root in random nearest neighbor trees [pdf].
with Anna Brandenberger, Elchanan Mossel, and Madhu Sudan.

Errors are Robustly Tamed in Cumulative Knowledge Processes [pdf].
with Anna Brandenberger, Elchanan Mossel, and Madhu Sudan.
Conference on Learning Theory (COLT) 2024.
Proceedings of the National Academy of Sciences (PNAS) 2025.

Uniformity Testing over Hypergrids with Subcube Conditioning [pdf].
with Xi Chen.
Symposium on Discrete Algorithms (SODA) 2024.

All author names are listed alphabetically, as is the convention in theoretical computer science and mathematics.

Teaching

At Harvard:

• Teaching Fellow for Essential Coding Theory (CS 229r) taught by Madhu Sudan (Fall 2023)

At Columbia, I was a Teaching Assistant for the following courses:

• Advanced Algorithms (COMS 4232) taught by Alexandr Andoni (Spring 2022)
• Introduction to Cryptography (COMS 4261) taught by Tal Malkin (Spring 2022)
• Analysis of Algorithms I (CSOR 4251) taught by Xi Chen (Summer 2021) and Alexandr Andoni (Fall 2021)
• Artificial Intelligence (COMS 4701) taught by Ansaf Salleb-Aouissi (Spring 2021)
• Discrete Mathematics: Combinatorics and Graph Theory (COMS 3203) taught by Ansaf Salleb-Aouissi (Fall 2020)

Other:

• TA for the PCMI Undergraduate Summer School on Quantum Computation (Summer 2023)
• I lectured and served as a TA for the Undergraduate Math Society's Introduction to Proofs workshop (Fall 2020, Fall 2021)

Fellowships and Selected Awards

• NDSEG Fellowship (2024)
• NSF GRFP Fellowship (2024, declined in favor of NDSEG)
• Magna cum laude, Columbia College (2022)
• John Jay Scholar – Columbia University Scholars Program (2018 - 2022)
• Verizon App Challenge: Best in Nation (2017)

Seminars and Organizations

• I currently organize TGINF, a theory seminar for graduate students and postdocs at Harvard.
• Columbia Undergraduate Learning Seminar in Theoretical Computer Science: Founder and Leader (Summer 2021 to Spring 2022). Organized reading groups on the analysis of Boolean functions and property testing (Summer 2021), A Theorist's Toolkit (Fall 2021), and High-Dimensional Probability and Applications to CS (Spring 2022).
• Columbia-Barnard Association for Women in Mathematics: Co-President (2021-2022). Organized reading groups on random walks (Summer 2020) and topology (Summer 2021).

Axioms

• Axiom 1. Mathematical potential is equally present in different groups, irrespective of geographic, demographic, and economic boundaries.
• Axiom 2. Everyone can have joyful, meaningful, and empowering mathematical experiences.
• Axiom 3. Mathematics is a powerful, malleable tool that can be shaped and used differently by various communities to serve their needs.
• Axiom 4. Every student deserves to be treated with dignity and respect.

Music