Sunay Joshi’s webpage

   


About

I am a doctoral student at UPenn interested in machine learning. I develop simple algorithms with theoretical guarantees that improve the reliability of artificial intelligence systems. Currently, I am exploring applications to natural language processing, image processing, AI-for-math, and econometrics. I am grateful to be advised by Prof Edgar Dobriban and Prof Hamed Hassani. Previously, I received my bachelor's degree in mathematics from Princeton with highest honors.

Focus

In the short term, I am focused on statistical approaches to AI reliability. In the medium term, I would like to explore the mathematical foundations of AI and economics. In the long term, I hope to build AI-powered systems that enable large-scale collaboration, and that help people express their analytical and artistic creativity en masse. I also hope to develop a statistical theory of venture investing.

Contact

My email address is sunayj [at] sas.upenn.edu and my desk is in Amy Gutmann Hall. Please reach out via email or social media, I would love to learn from you. (I find collaboration much more fun than working in isolation.) My curriculum vitae can be found here.

Other academic interests

I am also fascinated by and excited to learn more about single-cell gene sequencing methods like spatial transcriptomics; structural biology methods like cryo-EM; medical imaging methods like MRI; manifold learning; non-probabilistic and geometric foundations of ML and representation learning; approximation theory for ML; leveraging data symmetry and representation theory in the design of learning algorithms (i.e., neural architectures); treating neurological diseases by analyzing EEG signals and other diagnostics; auditing the medical reasoning of clinical LLMs via statistics; AI for conservation biology; multimodal AI and virtual reality for preserving historical cultures, artefacts, and spaces; auditing AI benchmarks via statistics; optimal control for robotics, macroeconometrics, steering generative AI (LLMs, diffusion models, flow matching models); mathematical statistical mechanics and its relation to probabilistic combinatorics, random matrix theory, and ML theory; the philosophy, foundations, and history of statistics; the precise relation between hierarchical and neural representations of data; analogies between optimization algorithms and stochastic and ordinary differential equations; mathematical and statistical finance and interpretable models of general multi-agent systems like mean-field games, especially in modeling financial crises; delineating the advantages of homogeneous vs heterogeneous agent swarms; network models in statistics; how AI agents handle uncertainty and ambiguity when deployed in complex settings; how to prevent p-hacking and other statistical crimes from being committed by data science AI agents; metacognitive algorithms for improving LLM performance; design choices when learning world models; anonymization and deanonymization of personal data on social media platforms; robustness, distribution shift, and out-of-distribution generalization in statistics and ML; algorithmic primitives for LLM jailbreaking and defenses; understanding why black-box Bayesian optimization works in practice, especially for drug discovery; analogies between statistics and analytic number theory; envisioning a future of "infinite-horizon" clinical trials; natural experiments on networks; leveraging synthetic data in statistics; creating simulacra of human behavior both individual and collaborative by leveraging novel qualitative psychometric factors; the interface of statistics and entrepreneurship, especially in the context of AI evaluation and monitoring; inventing more interactive and continuous modes of human-AI creative collaboration; co-creating personalized and aesthetic educational content using AI; cheaper music education with the help of AI and robotics; rethinking educational evaluation in the age of AI; improving home and public safety via passive AI-powered monitoring systems; extreme event prediction and mitigation; simple and generalizable hacks for boosting our collective physical health, mental health, and creativity; generative user interfaces; and designing scalable and inclusive academic workflows for our collective AI-empowered future.

Latest change: The Definition of Numerical Analysis

Profile picture Sunay Joshi

Publications

Preprints and papers.

Presentations

Notes

Things I wrote, some incomplete.
(More annotations are coming soon. For a few files, I include an Overleaf link; but most are PDFs, because I don't see myself frequently editing them.)

Math
  • ICM and STAI-X 2026 Notes
  • Advanced Calculus by Prof Dafermos

    A collection of simple lemmas that are frequently used in proofs in Fourier analysis, when developed using Riemann integration.

  • Fourier Analysis by Prof Dafermos

    A summary of what we covered in Fourier analysis.

  • Measure Theory by Dr Glaudo

    A summary of what we covered in measure theory and real analysis.

  • Differential Geometry Notes by Prof Dafermos

    An incomplete collection of notes from the differential geometry course at Princeton.

  • Differential Geometry Problems by Prof Dafermos

    These were our differential geometry homework problems. (Some, we never got around to solving.)

  • Representation Theory Notes by Prof Laga

    An incomplete summary of what we covered in our course on representation theory.

  • Probability Review under Prof Shkolnikov

    A summary of what we covered in probability theory.

  • Stochastic Calculus Review under Prof Hubert

    A summary of what we covered in stochastic calculus.

  • Differential Inequalities for the Random Cluster Model under Prof Aizenman

    My junior paper at Princeton: the derivation of a differential inequality that sheds light on the critical behavior of the Random Cluster Model (RCM) from statistical physics. The RCM is a dependent generalization of Bernoulli percolation, which has direct connections to the Ising and Potts models of ferromagnetism. The key input is a new concentration inequality for "decision trees" from the theoretical computer science community. I plan to elaborate on the broader role of differential inequalities in the study of phase transitions, as at first glance this might not be clear to the reader. I also plan to rewrite Section 4.1, whose exposition at present is a bit rushed.

  • Conformal Invariance in Percolation under Prof Aizenman

    One of the most striking results in percolation theory in two dimensions is conformal invariance, which states that when one takes an appropriate scaling limit of Bernoulli percolation on the integer lattice, crossing probabilities are invariant under conformal maps. This junior seminar paper explores implications of conformal invariance. In particular, I derive the crossing probability of an annulus up to constants.

  • Random Field Ising Model under Prof van Handel

    The study of disordered models in statistical mechanics is infamously challenging. The ultimate goal is to understand realistic models of magnets with impurities, like the Edwards--Anderson model; but at present, this is hopelessly out of reach. Here, we instead start with one of the simplest disordered models, the Random Field Ising Model (RFIM), and in this note I present an exposition of the proof that the RFIM does not exhibit a phase transition. The key idea is to treat the free energy as a function of the gaussian external field random variables, and then to leverage gaussian integration by parts and gaussian concentration. Once these are applied, bounding the free energy reduces to combinatorics. I plan on rewriting parts of this.

  • Cryo-EM Notes under Prof Singer and Prof Moscovich

    Incomplete notes on the math of cryo-electron microscopy.

  • Multimode Value Iterations under Prof Gee and Prof Vladimirsky

    Consider a partially-deterministic control problem where an agent navigates two-dimensional space, switching between multiple kinds of dynamics ("modes"). In this incomplete note, we analyze the convergence of value iterations for computing the value function, both in general, as well as under a monotonicity assumption on the mode transitions.

  • Elliptic Curve Cryptography under Dr Katharine Woo

    A summary of what I learned about elliptic curves and their applications to cryptography through Princeton's Directed Reading Program. Many of the cryptographic protocols listed in the report can be performed using an arbitrary abelian group. However, the group of rational points on an elliptic curve has a number of nice properties that can be leveraged.

  • Elliptic Curve Cryptography Notes

    The incomplete personal notes that were used to prepare the report above. The material on elliptic functions served as motivation for me to learn complex analysis.

  • Congruence of Linear Symplectic Forms under Prof Tang
  • Degenerate Turán Problem and Its Variants under Prof Jiang
  • Math Colloquium: Prof Deligne

    Incomplete notes from a talk on the hidden symmetries of algebraic varieties that went straight over my head.

  • Math Colloquium: Prof Fefferman

    Incomplete notes from a talk on interpolation and its relation to metric geometry.

  • Math Colloquium: Prof Sarnak

    Incomplete notes from a talk on the relationship between Diophantine equations and optimally navigating the special unitary group, with applications to the design of gates for quantum computing. (I am still trying to find my notes from this talk.)

  • PUMaC Problems I Wrote
Statistics
  • An Overview of Statistical Methodology by Prof Katsevich

    A gentle overview of the topics covered in the statistical methodology course at Penn, spanning linear models and their geometry, generalized linear models, statistical inference, resampling methods, model misspecification, robust statistics, the basics of multiple hypothesis testing, and quite a few interesting tidbits from the history of statistics (whose early days seem particularly messy and controversial compared to other parts of the mathematical sciences).

  • Mathematical Statistics Review under Prof Cattaneo

    A summary of what we covered in mathematical statistics.

  • Mathematical Statistics Notes by Prof Bhattacharya

    Handwritten notes from the mathematical statistics course at Penn.

  • High-Dimensional Asymptotics

    Notes on high-dimensional statistics, including the basics of random matrix theory and universality.

  • Statistical Physics for ML

    A leisurely overview of topics in equilibrium statistical mechanics, with an emphasis on spin glasses, and with an explanation of how such concepts relate to modern problems in high-dimensional statistics and optimization.

  • Estimation in Ising Models under Prof Bhattacharya

    An exposition of results concerning the estimation of the inverse-temperature and external field in Ising models. Maximum likelihood estimation is intractable in this setting due to the usual difficulties (?) posed by the partition function. Luckily, the maximum pseudolikelihood estimator is consistent and achieves low asymptotic variance. Taking a step back, I find this problem a bit unnatural from an applied perspective.

  • VAEs and the EM Algorithm on Dwip's Blog

    A blog post Dwip and I wrote about variational autoencoders, an early form of generative AI.

  • Diffusion Models

    An incomplete overview of diffusion models, and the related theory of stochastic localization. Since writing these notes, I've greatly clarified my understanding of stochastic localization with the help of Shervin Khalafi, and plan on updating the file accordingly.

  • Quantifying single-cell differential abundance with density difference estimation on manifolds under Prof Chitra, Dr Gold, and Prof Raphael
  • Power-Law Graph Alignment under Prof Sly

    The subset of my senior thesis that does not appear in existing papers. My broader thesis was on the alignment of correlated random graphs. Graph alignment algorithms can be used to positive ends (aligning protein--protein interaction networks), as well as to less positive ends (deanonymizing social networks).

Economics
Reflections
  • Ruminations on AI Safety

    Many mathematicians have begun to think seriously about AI safety, recognizing both the sea change taking place in their native fields, as well as the practical urgency of alignment. In this file, I record some of my preliminary thoughts.

  • Perspective on Future of Papers

    A personal perspective on how the academic publishing system in applied mathematics should evolve in this disorienting new era of superhuman AI.

  • Perspective on Rating One's Own Papers

    As a beginning graduate student, one aspect of academic culture that I found particularly disorienting was the tendency for all researchers to sell their latest paper as "the next big thing". (The advance of AI has only served to exacerbate this problem, in my experience.) In reality, most of a researcher's scholarly output serves merely to fulfill one of many obligations (either to a grant that funds their lab, or to students who must be trained by working on simple research problems), and such work has no ambition of changing the world. Of course, this doesn't stop researchers from overselling their papers, due to various perverse incentives that exist. In this incomplete note, I brainstorm schemes to address this problem, taking inspiration from Prof Su's "rank your own paper" mechanism for improved peer review in ML conferences. I first imagine an ideal world where tenured researchers are honest and attempt themselves to construct (absolute, not relative) scores for each of their own papers. I then acknowledge that such a system is extremely unlikely to take hold in academia, even among researchers with job security; and as a result, propose a scheme to estimate the unobservable quality of a given lab's papers based on observable factors, like the venue it is submitted to, whether or not it is featured on the lab website, the amount of social media promotion that was attempted, and so on. The goal is not at all to denigrate particular papers, but simply to help new researchers obtain a "calibrated" view of the research literature.

  • Letter to Freshman Me

    Recently, a freshman at Princeton wrote to me, asking what I do and how I got here. I'm not sure if he was impressed by or dismayed at my path through life thus far, but I gave him my advice, with the wisdom afforded by two long years outside of the orange bubble. I think some points apply pretty broadly.

Seminar Notes

My Seminar Notes

Things written by others about math; which I've read, am reading, or will read.

Seminars

Places

Blogs

Inspiration

Math
Statistics
Economics

Resources

Things that may be helpful at all levels.

I personally find that music, art, and exercise are three activities that help me be more creative in life in general, and at research in particular. Below are some resources that I've found useful.

I love educational materials that combine science and art (especially animation). I think it'd be great if more scientists and artists teamed-up towards this purpose. Check out some examples below.

Outreach

  • Undergraduate Course Assistant for MAT340: Applied Algebra at Princeton, taught by Prof McConnell
  • Mentor for UPenn Math Directed Reading Program
  • Volunteer/Member, GETUP-UAW Local 5124 at Penn
  • Applied Math Rep for SASGov
  • Student Volunteer, ICML 2026 Workshop on AI4Research
  • Organizer, Dobriban Statistical Machine Learning Reading Group 2024-25
  • Organizer, Hassani Group Running Club
  • (Tentative) Member, Sargent Reading Group at Wharton 2026-27
  • Co-Advising Chair with Sara Ansari, Princeton Mathematics Club 2023-24
  • Problem Czar, PUMaC 2022, and PUMaC problem writer
  • Co-Director with Sameer Pai of Joe Holbrook Memorial Math Competition, 2019

Awards

  • NSF Graduate Research Fellowship Program, Honorable Mention (2024): National recognition for a meritorious application to NSF's graduate research fellowship program.
  • Phi Beta Kappa (2024): Elected to the oldest academic honor society in the United States.
  • Sigma Xi (2024): Elected to the scientific research honor society.
  • Andrew H. Brown Prize, Princeton University (2023): Awarded by the Mathematics Department to outstanding juniors in mathematics.
  • Class of 1861 Prize, Princeton University (2022): Awarded to the sophomore with the best record on the Putnam Examination.
  • Shapiro Prize for Academic Excellence, Princeton University (2021): Recognizes outstanding academic achievement by undergraduates in their first or second years of study.
  • William Lowell Putnam Mathematical Competition, Rank 150 (2021): An annual undergraduate mathematics competition organized by the Mathematical Association of America.
  • USA Physics Olympiad, Silver Medalist (2019): A national high-school physics examination used in selecting the U.S. Physics Team.
  • USA Junior Math Olympiad, Qualifier (2018): A national invitational mathematics competition focused on proof-based problem solving.

Artwork

My attempts at art, and things I find pretty. (Update: no longer being updated, see my Facebook for the latest.)

Thinking in progress shadow portrait Low-poly walking figure with light trails Walk path in Shirdi Creation photo IMG 0098 Creation photo IMG 0177 Creation photo IMG 0292 Creation photo IMG 0405 Creation photo IMG 0538 Creation photo IMG 0633 Artwork image IMG 0950
Wildlife mural with a leopard and deer beneath a tree
Minor AI denoising was done.
Artwork image IMG 0859
Dog resting beside a sidewalk in Mira Road
Minor AI denoising was done.
Pink flower covered in raindrops in sharp focus, with a cyclist blurred in motion behind it
Fisher psych artwork Quote about a quiet life, useful work, nature, books, music, and love for one's neighbor Black-and-white portrait beside a chalkboard, next to a statue labeled Claude Elwood Shannon Discussion quoting Richard Feynman and Hironaka on learning and making new discoveries Screenshot of Birth of a Theorem, featuring Cédric Villani in the snowy Institute woods in 2009 Newspaper article titled The search for the good life, featuring a portrait of John Maynard Keynes Text excerpt titled A Fateful Stopover in Ohio
Regime-switching visualization with colored bands and jagged lines
Regimes, switching