David Cheikhi

David Cheikhi is a PhD candidate in the Decision, Risk and Operations division of Columbia Business School, advised by Daniel Russo, working on reinforcement learning theory, temporal-difference learning and sequential decision making. He competed for France at the International Olympiad in Informatics (IOI) in 2014, winning a bronze medal, and studied at Lycee Henri Poincare (CPGE MP) and Ecole Polytechnique before moving to Columbia. He has held software/data internships at Google (2018, 2019, 2020) and Faire (2024), and a quantitative-research internship at Two Sigma (summer 2025).

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• Quant employment verification: CONFIRMED. Cheikhi held a Quantitative Researcher role at Two Sigma (New York City), listed as Jun 2025 - Aug 2025 (3 months). Identity is supported: the same LinkedIn profile carries the Columbia OR PhD headline and the Two Sigma role, matching his personal site and publication record. Two Sigma (twosigma.com) is a quantitative hedge fund / systematic investment manager, so the employer classification is valid. Evidence is LinkedIn/index-derived rather than an independent company page, so exact title and dates are index-only. No other quantitative-finance employment (bank, asset manager, energy/crypto trading) was found.
• Quantitative Researcher at Two Sigma, New York City, Jun 2025 - Aug 2025 (3 months).Jun 2025
• His entire pre-PhD career is at big-tech and marketplace firms (Google x3, Faire), not finance; Two Sigma 2025 is the only quant-finance entry and it is a 3-month summer stint.
• PhD candidate in the Decision, Risk and Operations division of Columbia Business School, advised by Daniel Russo, working on reinforcement learning theory and temporal-difference learning.
• First-authored ICML 2023 paper 'On the Statistical Benefit of Temporal Difference Learning' with Dan Russo, accepted as an oral (arXiv Jan 2023, revised Feb 2024).Jan 30, 2023
• Won a bronze medal for France at the International Olympiad in Informatics (IOI) 2014 in Taiwan with 272 points.Jul 2014
• Software Engineer Intern at Google in London (2018), Software Engineer Intern (Operations Research) in Paris (2019), Research Software Engineer Intern in Paris (2020) - three separate Google internships.
• Listed in Daniel Russo's Columbia CV ('fifth year PhD student', Jan 2026), placing his PhD start around 2021.Jan 2026
• Second first-author paper with Dan Russo, 'On the Limited Representational Power of Value Functions and its Links to Statistical (In)Efficiency' (arXiv, Mar 2024).Mar 11, 2024
• Data Scientist Intern at Faire (New York City) in 2024, during the Columbia PhD.2024
• Co-author on 'Stochastic Flows and Geometric Optimization on the Orthogonal Group', ICML 2020, in a large author list (Choromanski et al.) - his earliest publication, predating the PhD.2020
• Google's own blog features him on National Intern Day as a Software Engineering Intern, Operations Research, Ecole Polytechnique, Paris office.2019