Will Ma Roderick H. Cushman Associate Professor Decision, Risk, and Operations, Graduate School of Business and Data Science Institute Columbia University Email: wm2428 (at) gsb (dot) columbia (dot) edu Office: Kravis 951

Research

• Online Algorithms: (stochastic) online matching, prophet inequalities, contention resolution schemes, stochastic knapsack, algorithms with predictions
• Revenue Management: (dynamic) assortment optimization, product ranking, network revenue management, reusable resources, bundling
• E-commerce Supply Chains: inventory, placement, fulfillment
• Other Topics: neural network verification, fairness, hiring

Teaching & Students (I am unable to respond to most inquiries regarding openings for Ph.D. positions, as admissions are handled at the departmental level.)

Service

• Associate Editor for journals: Operations Research, Management Science
• Program Committee for conferences: EC 2025 (senior), EC 2024 (senior), WINE 2023 (senior), EC 2023, WINE 2022, EC 2022, WINE 2021, EC 2021
• Co-organizer of conferences: RMP 2025 (INFORMS Revenue Management & Pricing section conference), DSL70 (workshop in honor of David Simchi-Levi's 70th birthday) in 2025, NYC Ops Day 2024, NYC Ops Day 2023, RMP cluster at INFORMS 2022

Miscellaneous

  I play piano at Sid Gold's karaoke bar in Manhattan! next event Wed Oct 30 7-9pm // mailing list // song list

♠♥ I used to be a poker player and taught a poker course that is on MIT OpenCourseWare

I co-founded video game start-up Lunarch Studios and designed the strategy game Prismata

Some summary writings about problems I work on:

• Randomized Rounding Approaches to Online Allocation, Sequencing, and Matching

  INFORMS Tutorials, 2024

  *featured in ACM SIGACT News, September 2024 issue

• Assortment Optimization: An Annotated Reading Assortment

  ACM SIGecom Exchanges, 2024

Working Papers/Under Revision (reverse chronological order of last update)

• Potential-Based Greedy Matching for Dynamic Delivery Pooling with Hongyao Ma, Matias Romero

• Forward-backward Contention Resolution Schemes for Fair Rationing with Calum MacRury, Cliff Stein

• From Contextual Data to Newsvendor Decisions: On the Actual Performance of Data-Driven Algorithms with Omar Besbes, Omar Mouchtaki

  [J] Major Revision in Management Science

• Real-Time Personalized Order Holding with Mohammad Reza Aminian, Linwei Xin

  [J] R & R in Management Science

  *covered in Chicago Booth Review, 2024

• Online Contention Resolution Schemes for Network Revenue Management and Combinatorial Auctions with Calum MacRury, Jingwei Zhang

• Dynamic Pricing for Reusable Resources: The Power of Two Prices with Santiago Balseiro, Wenxin Zhang

  [J] Major Revision in Operations Research

• Online Bipartite Matching with Advice: Tight Robustness-Consistency Tradeoffs for the Two-Stage Model with Billy Jin

  [J] R & R in Management Science

  [C] Neural Information Processing Systems (NeurIPS), 2022

  *Billy Jin was Winner of Student Paper Prize of INFORMS Decision Analysis Society, 2023

• Survey of Data-driven Newsvendor: Unified Analysis and Spectrum of Achievable Regrets with Zhuoxin Chen

  [J] Major Revision in Operations Research

• VC Theory for Inventory Policies with Yaqi Xie, Linwei Xin

  *selected for presentation in the MSOM Supply Chain Management SIG, 2024

• Online Matching and Contention Resolution for Edge Arrivals with Vanishing Probabilities with Calum MacRury, Pranav Nuti

  [C] Economics and Computation (EC), 2024

• A Nonparametric Framework for Online Stochastic Matching with Correlated Arrivals with Ali Aouad

  [J] Major Revision in Management Science

  [C] Economics and Computation (EC), 2023

• Optimizing Inventory Placement for a Downstream Online Matching Problem with Boris Epstein

  [J] Major Revision in Manufacturing & Service Operations Management

  *Boris Epstein was a Finalist in the George E. Nicholson Student Paper Competition, 2024

• Random-order Contention Resolution via Continuous Induction: Tightness for Bipartite Matching under Vertex Arrivals with Calum MacRury

  [C] Symposium on Theory of Computing (STOC), 2024

• The Competitive Ratio of Threshold Policies for Online Unit-density Knapsack Problems with David Simchi-Levi, Jinglong Zhao

  [J] Minor Revision in Management Science

  *Jinglong Zhao earned an Honorable Mention in the POMS Hong Kong Student Paper Competition, 2020

• Multi-Stage and Multi-Customer Assortment Optimization With Inventory Constraints with Elaheh Fata, David Simchi-Levi

Publications (in [J] ournals and [C] onferences)

• Beyond IID: Data-Driven Decision-Making in Heterogeneous Environments with Omar Besbes, Omar Mouchtaki

  [J] Management Science, forthcoming

  [C] Neural Information Processing Systems (NeurIPS), 2022

• The Benefits of Delay to Online Decision-Making with Yaqi Xie, Linwei Xin

  [J] Management Science, forthcoming

  *covered in Chicago Booth Review, 2023

  *selected for presentation in the MSOM Supply Chain Management SIG, 2023

• Tightness without Counterexamples: A New Approach and New Results for Prophet Inequalities with Jiashuo Jiang, Jiawei Zhang

  [J] Mathematics of Operations Research, forthcoming

  [C] Economics and Computation (EC), 2023

• Degeneracy is OK: Logarithmic Regret for Network Revenue Management with Indiscrete Distributions with Jiashuo Jiang, Jiawei Zhang

  [J] Operations Research, articles in advance

• Sample Complexity of Posted Pricing for a Single Item with Billy Jin, Thomas Kesselheim, Sahil Singla

  [C] Neural Information Processing Systems (NeurIPS), 2024 (Spotlight)

• Fair Secretaries with Unfair Predictions with Eric Balkanski, Andreas Maggiori

  [C] Neural Information Processing Systems (NeurIPS), 2024

• Group-level Fairness Maximization in Online Bipartite Matching with Pan Xu, Yifan Xu

  [C] Neural Information Processing Systems (NeurIPS), 2024

  *abstract accepted for presentation at Autonomous Agents and Multi-Agent Systems (AAMAS), 2022

• Improved Guarantees for Offline Stochastic Matching via new Ordered Contention Resolution Schemes with Brian Brubach, Nathaniel Grammel, Aravind Srinivasan

  [J] Mathematics of Operations Research, articles in advance

  [C] Neural Information Processing Systems (NeurIPS), 2021

• Leveraging the degree of Dynamic Substitution in Assortment and Inventory Planning with Jingwei Zhang, Huseyin Topaloglu

  [J] Operations Research (Technical Note), articles in advance

• On (Random-order) Online Contention Resolution Schemes for the Matching Polytope of (Bipartite) Graphs with Calum MacRury, Nathaniel Grammel

  [J] Operations Research, articles in advance

  [C] Symposium on Discrete Algorithms (SODA), 2023

• Tight Guarantees for Multi-unit Prophet Inequalities and Online Stochastic Knapsack with Jiashuo Jiang, Jiawei Zhang

  [J] Operations Research, articles in advance

  [C] Symposium on Discrete Algorithms (SODA), 2022

  *Jiashuo Jiang was a Finalist in the George E. Nicholson Student Paper Competition, 2022

  *Jiashuo Jiang was a Finalist for the Jeff McGill Student Paper Award for Revenue Management and Pricing, 2021

• Online Matching Frameworks under Stochastic Rewards, Product Ranking, and Unknown Patience with Brian Brubach, Nathaniel Grammel, Aravind Srinivasan

  [J] Operations Research, articles in advance

  [C] Artificial Intelligence and Statistics (AISTATS), 2021

  Previous title: Follow Your Star: New Frameworks for Online Stochastic Matching with Known and Unknown Patience

• Order Selection Problems in Hiring Pipelines with Boris Epstein

  [J] Operations Research, 2024

  [C] Web and Internet Economics (WINE), 2022

• Optimizing for Strategy Diversity in the Design of Video Games with Oussama Hanguir, Jiangze Han, Christopher Thomas Ryan

  [J] Mathematical Programming, 2024

  [C] Integer Programming and Combinatorial Optimization (IPCO), 2023

• Assortment Planning for Recommendations at Checkout under Inventory Constraints with Xi Chen, David Simchi-Levi, Linwei Xin

  [J] Mathematics of Operations Research, 2024

  *1st Place, Chinese Scholars Association for Management Science and Engineering (CSAMSE) Best Paper Award, 2017

  *covered in Chicago Booth Review, 2018

• Tight Guarantees for Static Threshold Policies in the Prophet Secretary Problem with Nick Arnosti

  [J] Operations Research, 2023

  [C] Economics and Computation (EC), 2022

• Order-optimal Correlated Rounding for Fulfilling Multi-item E-commerce Orders

  [J] Manufacturing & Service Operations Management, 2023

  [C] Economics and Computation (EC), 2023

  *accepted for presentation at Applied and Computational Discrete Algorithms (ACDA), 2023

  *invited for presentation in Online Algorithms & Online Rounding workshop at FOCS 2023

  *selected for presentation in the MSOM Supply Chain Management SIG, 2022

• When is Assortment Optimization Optimal?

  [J] Management Science, 2023

  [C] Economics and Computation (EC), 2022

  *2nd Place, Rothkopf Junior Researcher Paper Prize for Auctions and Market Design, 2021

  *selected for spotlight presentation in the INFORMS Revenue Management and Pricing Conference, 2022

  *selected for presentation in the MSOM Service SIG, 2021

• Fairness Maximization among Offline Agents in Online-Matching Markets with Pan Xu, Yifan Xu

  [J] ACM Transactions on Economics and Computation (TEAC), 2023

  [C] Web and Internet Economics (WINE), 2021

• Constructing Demand Curves from a Single Observation of Bundle Sales with David Simchi-Levi

  [C] Web and Internet Economics (WINE), 2022

  Previous title: Learning Valuation Distributions from Bundle Sales

• Revenue-Optimal Deterministic Auctions for Multiple Buyers with Ordinal Preferences over Fixed-Price Items

  [J, invited] ACM Transactions on Economics and Computation (TEAC), 2022

  [C] Web and Internet Economics (WINE), 2020

• Bifurcating Constraints to Improve Approximation Ratios for Network Revenue Management with Reusable Resources with Jackie Baek

  [J] Operations Research (Technical Note), 2022

• Distributionally Robust Linear and Discrete Optimization with Marginals with Louis Chen, Karthik Natarajan, David Simchi-Levi, Zhenzhen Yan

  [J] Operations Research, 2022

• Inventory Balancing with Online Learning with Wang Chi Cheung, David Simchi-Levi, Xinshang Wang

  [J] Management Science, 2022

• Reaping the Benefits of Bundling under High Production Costs with David Simchi-Levi

  [C] Artificial Intelligence and Statistics (AISTATS), 2021

• Dynamic Pricing (and Assortment) under a Static Calendar with David Simchi-Levi, Jinglong Zhao

  [J] Management Science, 2021

• On Policies for Single-leg Revenue Management with Limited Demand Information with David Simchi-Levi, Chung-Piaw Teo

  [J] Operations Research, 2021

• Algorithms for Online Matching, Assortment, and Pricing with Tight Weight-dependent Competitive Ratios with David Simchi-Levi

  [J] Operations Research, 2020

  [C] Economics and Computation (EC), 2019

  Previous title: Tight Weight-dependent Competitive Ratios for Online Edge-weighted Bipartite Matching and Beyond

  *Finalist, George E. Nicholson Student Paper Competition, 2017

• The Convex Relaxation Barrier, Revisited: Tightened Single-Neuron Relaxations for Neural Network Verification with Christian Tjandraatmadja, Ross Anderson, Joey Huchette, Krunal Patel, Juan Pablo Vielma

  [C] Neural Information Processing Systems (NeurIPS), 2020

• Separation between Second Price Auctions with Personalized Reserves and the Revenue Optimal Auction with Balasubramanian Sivan

  [J] Operations Research Letters, 2020

• Strong Mixed-Integer Programming Formulations for Trained Neural Networks with Ross Anderson, Joey Huchette, Christian Tjandraatmadja, Juan Pablo Vielma

  [J] Mathematical Programming, 2020

• Distributionally Robust Max Flows with Louis Chen, Jim Orlin, David Simchi-Levi

  [C] Symposium on Simplicity in Algorithms (SOSA), 2020

• Improvements and Generalizations of Stochastic Knapsack and Markovian Bandits Approximation Algorithms

  [J] Mathematics of Operations Research, 2018

  [C] Symposium on Discrete Algorithms (SODA), 2014

  *2nd place, INFORMS Optimization Society Student Paper Competition, 2017

• Predicting User Choice in Video Games with Arjun Khandelwal, David Simchi-Levi, and in partnership with Prismata

  Presentation slides, 2017

• A Geometric Approach to Combinatorial Fixed-point Theorems with Elyot Grant

  [C] European Conference on Combinatorics, Graph Theory and Applications (EUROCOMB), 2013

• The Approximability and Integrality Gap of Interval Stabbing and Independence Problems with Shalev Ben-David, Elyot Grant, Malcolm Sharpe

  [C] Canadian Conference on Computational Geometry (CCCG), 2012

• Packing and Covering Triangles in Planar Graphs with Qing Cui, Penny Haxell

  [J] Graphs and Combinatorics, 2009