Ethan X. Fang

activity

20142026

most citedAccelerating Stochastic Composition Optimization

24 citations · 96 across the 31 of their papers we have counts for

collaborators

35 papers

cs.LG2026

PerSPL: Personalized Semi-supervised Preference Learning

Xiaoan Xu, Tingzhou Wei, Juncheng Dong +3

Personalized reward models require user-specific preference comparisons, but collecting such feedback is costly and provides only limited supervision for each user. At the same tim…

cs.AI2026

DUDA-Bench: Benchmarking LLM Agents on Multimodal Data-Driven Urban Diagnosis

Yizhi Song, Hang Ni, Weijia Zhang +1

Urban diagnosis integrates heterogeneous observations to identify urban problems, localize affected areas, and investigate contributing factors, informing evidence-based urban plan…

cs.DS2026

Vector Balancing in Polynomial Time

Shengtao Guo, Ethan X. Fang, Junwei Lu

We present a spectral signing algorithm solving the Komlós problem with a constant discrepancy in polynomial time. Given a matrix $A \in R^{m \times n}$ whose columns have Eu…

math.CO2026

Unimodality of Independence Polynomials for Sufficiently Large Forests

Ethan X. Fang, Junwei Lu, Eran Nevo +2

We prove that the independence sequence of every sufficiently large forest is unimodal. The result follows from establishing log-concavity on a central interval of the sequence, al…

math.DG2026

A Two-Stage Construction of Positive Curvature on the Gromoll-Meyer Sphere

Shengtao Guo, Ethan X. Fang, Junwei Lu

We construct an explicit one-parameter family of smooth metrics on the Gromoll-Meyer exotic seven-sphere, converging in $C^{\infty}$ to a fixed further Cheeger deformation of the Esc…

math.CO2026

Vector Balancing via Directional Total Variation

Shengtao Guo, Ethan X. Fang, Junwei Lu

Our main result is a $3 2 π$ bound for the Komlós signing problem: every finite family of real vectors of Euclidean norm at most one admits a signed sum of $ℓ_{\infty}$ -norm…

math.FA2026

An Improved Lower Bound for the Complex Grothendieck Constant

Shengtao Guo, Ethan X. Fang, Junwei Lu

We prove $K_{G}^{C} > 1.35584631827168$ for the classical complex Grothendieck constant, closing more than one quarter of the gap between Davie's lower bound and Haagerup's up…

math.DG2026

A Metric with Positive Sectional Curvature on $S^{3} \times S^{3}$

Shengtao Guo, Ethan X. Fang, Junwei Lu

We construct a smooth Riemannian metric with strictly positive sectional curvature on $S^3\times S^3$. Since $S^3\times S^3$ is even-dimensional and has Euler characteristic ze…

math.CO2026

On Unavoidable Faces of High-Dimensional Polytopes

Jesús A. De Loera, Ethan X. Fang, Shengtao Guo +2

Kalai's cube--simplex conjecture asserts that for all positive integers $ℓ, k$ , there is an integer $f (ℓ, k)$ such that every polytope of dimension at least $f (ℓ, k)$ has eit…

math.GM2026

A Complex Structure on $S^{2} \times S^{4}$

Shengtao Guo, Ethan X. Fang, Junwei Lu

We show that $S^{2} \times S^{4}$ admits a complex structure. Starting from a modular family of complex two-tori associated with the $(3, 4, \infty)$ triangle group and the compactificati…

math.DG2026

A Metric with Positive Sectional Curvature on $S^{2} \times S^{3}$

Shengtao Guo, Ethan X. Fang, Junwei Lu

We prove that $S^{2} \times S^{3}$ admits a Riemannian metric with positive sectional curvature. We view it as a principal circle bundle over $S^{2} \times S^{2}$ . A diagonal Cheeger deforma…

math.PR2026

Weak-Type Bounds for Convolution on the Boolean Hypercube

Junwei Lu, Shengtao Guo, Ethan X. Fang

Let $G$ be the Boolean hypercube which carries uniform measure $λ$ , and let $T_{μ}$ denote convolution by a finite positive measure $μ$ on $G$ . For $ψ_μ(u)=\sup\{uλ(\{T_μf\geq u\}):f…

cs.LG2026

Diffusion-Based Data-Driven Assortment Optimization

Junyi Liao, Xiaohui Jiang, Zhengwei Tong +2

Assortment optimization is a fundamental problem in revenue management, typically addressed using parametric choice models such as the multinomial logit (MNL) and its variants. Whi…

math.CO2026

Sharp Bounds on the Independence Number of Simplicial Spheres

Jesús A. De Loera, Ethan X. Fang, Junwei Lu +2

We study the maximum size of an independent set in the graph of a simplicial sphere. Let $β (d, n)$ denote this maximum over all simplicial $(d - 1)$ -spheres on $n$ vertices, and let $…

cs.AI2026

Hypothesis-Disciplined Multi-Agent Automated Formalization of Asymptotic Statistical Theory

Tingzhou Wei, Zeyu Zheng, Ethan X. Fang +1

Asymptotic statistical theory is a challenging domain for AI-assisted formalization: its central results mix convergence statements, asymptotic expansions, functional analysis, and…

cs.LG2026

Decoding Rewards in Competitive Games: Inverse Game Theory with Entropy Regularization

Junyi Liao, Zihan Zhu, Ethan Fang +2

Estimating the unknown reward functions driving agents' behaviors is of central interest in inverse reinforcement learning and game theory. To tackle this problem, we develop a uni…

cond-mat.mes-hall2025

Electric field tunable magnetoexcitons in Xenes-hBN-TMDC, Xenes-hBN-BP, and Xenes-hBN-TMTC heterostructures

Roman Ya. Kezerashvili, Anastasia Spiridonova, Klaus Ziegler

In this work, we propose novel van der Waals (vdW) heterostructures composed of Xenes, transition metal dichalcogenides (TMDCs), phosphorene, and transition metal trichalcogenides…

math.ST2024

Anti-Concentration Inequalities for the Difference of Maxima of Gaussian Random Vectors

Alexandre Belloni, Ethan X. Fang, Shuting Shen

We derive novel anti-concentration bounds for the difference between the maximal values of two Gaussian random vectors across various settings. Our bounds are dimension-free, scali…

math.ST2023★ 1 cited

Pivotal Estimation of Linear Discriminant Analysis in High Dimensions

Ethan X. Fang, Yajun Mei, Yuyang Shi +2

We consider the linear discriminant analysis problem in the high-dimensional settings. In this work, we propose PANDA(PivotAl liNear Discriminant Analysis), a tuning-insensitive me…

cs.LG2023★ 1 cited

PASTA: Pessimistic Assortment Optimization

Juncheng Dong, Weibin Mo, Zhengling Qi +3

We consider a class of assortment optimization problems in an offline data-driven setting. A firm does not know the underlying customer choice model but has access to an offline da…

stat.ML2023

Combinatorial Inference on the Optimal Assortment in Multinomial Logit Models

Shuting Shen, Xi Chen, Ethan X. Fang +1

Assortment optimization has received active explorations in the past few decades due to its practical importance. Despite the extensive literature dealing with optimization algorit…

math.OC2022★ 1 cited

Stochastic Compositional Optimization with Compositional Constraints

Shuoguang Yang, Wei You, Zhe Zhang +1

Stochastic compositional optimization (SCO) has attracted considerable attention because of its broad applicability to important real-world problems. However, existing works on SCO…

stat.ML2021★ 18 cited

Lagrangian Inference for Ranking Problems

Yue Liu, Ethan X. Fang, Junwei Lu

We propose a novel combinatorial inference framework to conduct general uncertainty quantification in ranking problems. We consider the widely adopted Bradley-Terry-Luce (BTL) mode…

cs.LG2021

Implicit Regularization of Bregman Proximal Point Algorithm and Mirror Descent on Separable Data

Yan Li, Caleb Ju, Ethan X. Fang +1

Bregman proximal point algorithm (BPPA) has witnessed emerging machine learning applications, yet its theoretical understanding has been largely unexplored. We study the computatio…

PerSPL: Personalized Semi-supervised Preference Learning

DUDA-Bench: Benchmarking LLM Agents on Multimodal Data-Driven Urban Diagnosis

Vector Balancing in Polynomial Time

Unimodality of Independence Polynomials for Sufficiently Large Forests

A Two-Stage Construction of Positive Curvature on the Gromoll-Meyer Sphere

Vector Balancing via Directional Total Variation

An Improved Lower Bound for the Complex Grothendieck Constant

A Metric with Positive Sectional Curvature on S3×S3

On Unavoidable Faces of High-Dimensional Polytopes

A Complex Structure on S2×S4

A Metric with Positive Sectional Curvature on S2×S3

Weak-Type Bounds for Convolution on the Boolean Hypercube

Diffusion-Based Data-Driven Assortment Optimization

Sharp Bounds on the Independence Number of Simplicial Spheres

Hypothesis-Disciplined Multi-Agent Automated Formalization of Asymptotic Statistical Theory

Decoding Rewards in Competitive Games: Inverse Game Theory with Entropy Regularization

Electric field tunable magnetoexcitons in Xenes-hBN-TMDC, Xenes-hBN-BP, and Xenes-hBN-TMTC heterostructures

Anti-Concentration Inequalities for the Difference of Maxima of Gaussian Random Vectors

Pivotal Estimation of Linear Discriminant Analysis in High Dimensions

PASTA: Pessimistic Assortment Optimization

Combinatorial Inference on the Optimal Assortment in Multinomial Logit Models

Stochastic Compositional Optimization with Compositional Constraints

Lagrangian Inference for Ranking Problems

Implicit Regularization of Bregman Proximal Point Algorithm and Mirror Descent on Separable Data

A Metric with Positive Sectional Curvature on $S^{3} \times S^{3}$

A Complex Structure on $S^{2} \times S^{4}$

A Metric with Positive Sectional Curvature on $S^{2} \times S^{3}$