Experience & leadership

Résumé

The short version of my working life. The rest of the site goes deeper on teaching, ICPC, and research.

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Summary

New York, NY

I build systems that must remain reliable under real-world pressure—and the evaluation and feedback loops that make them improve.

Fifteen years across Google, Two Sigma, and startups; currently Chief Architect at Probook. My work spans production AI architecture, empirical evaluation, mathematical research, and technical organizations. I also teach at Columbia and direct the ICPC Foundation’s internship program.

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Three focused one-page versions

Professional Experience

2026 — Present

Chief Architect

Probook — the AI operating system for home services

  • Serve as Chief Architect at Probook, which publicly describes its platform as one connected system for the front-office customer experience, built around dispatch.
  • Product capabilities, company news, and customer outcomes are available from Probook’s public website; unpublished company information is intentionally excluded from this résumé.
2025

VP Engineering

Arklex AI — Agent-First Organization

  • Directed development of an open-source framework for task-graph execution, distributed agent workflows, observability, and continuous delivery.
  • Turned a broad product thesis into an integrated Python system spanning 169 modules and roughly 175K lines.
2022 — 2023

Senior Quantitative Software Engineer

Two Sigma Investments

Worked on execution systems for systematic trading strategies — measuring and improving how orders actually get filled.

2016 — 2022

Research Software Engineer & Tech Lead

Google

Applied AI research that shipped into Google products, and core infrastructure for large-scale ML research. Tech lead for Google Kick Start, which grew from a regional contest into a competition with 110K+ participants worldwide.

Selected Technical Work

Public overview →
2026 · Published framework

Production decision-making

A reusable framework for making explicit, reviewable choices across quality, cost, risk, delivery time, and reversibility without publishing employer-specific measurements.

Read the framework →

Cascade centrality

Combined exact hardness, approximation, structural analysis, counterexamples, and rational-arithmetic computation in an active research program with Josh Alman.

Research overview →
2026 · Release gates

Contest engineering

Built validation discipline around high-stakes problem packages: independent solutions, adversarial submissions, generated data, automated checks, and human sign-off.

Engineering overview →

Leadership

2022 — Present

ICPC Foundation

Director of Internships (2025–) · Chair, CLI Symposium (2023–) · Co-Chair, Curriculum Committee

I run the Foundation’s internship program — 136 completed internships and 14 interns active as of August 14, 2026, across projects like the ICPC Archive, mobile app, and online training platform. I also chair the Competitive Learning Institute Symposium at the World Finals and co-chair an open-source curriculum covering 50+ algorithmic topics (50K+ downloads).

ICPC leadership →

2022 — Present

Columbia University

Adjunct, Department of Computer Science

Fourteen course offerings through Fall 2026 in competitive programming and interview preparation, reaching 500+ students — evaluation results published in full, rough semesters included. 100+ individual mentees, with placements verified and listed.

Courses → · Mentorship →

2024 — Present

The Journal of Competitive Learning

Senior Editor — peer-reviewed, open access

Launched the inaugural issue (Vol. 1, No. 1, May 2025), featuring a co-authored review article, “Programming Contests, Competitive Programming Curricula, and how Everybody Benefits.”

Honors & Awards

Full citations →
2026

Trainer Recognition — ICPC México Training Camp

ICPC México · Guadalajara, Jalisco

2025

Outstanding Problem Advisory — Taking the Field Medal

ICPC Challenge powered by Huawei

2025

Outstanding Mentorship — Quatrefoil Medal

ICPC Challenge powered by Huawei · Back-to-back recipient

2024

Outstanding Mentorship — Quatrefoil Medal

ICPC Challenge powered by Huawei · First of two consecutive awards

2024

Silver Medal — Coach, Columbia-CU later

3rd place · ICPC North America Championship

2023

Excellence in Leadership Award

ICPC North America

Complete award citations and source material: Honors & Recognition →

Education

Entered 2013

Massachusetts Institute of Technology

PhD, Operations Research (on leave) · Advisor: Asuman Ozdaglar

Research on network effects, information cascades, and game theory in complex systems.

2013

Stanford University

MS, Computer Science · Advisor: Fei-Fei Li

Focus on machine learning, computer vision, and scalable AI systems.

2011

Stanford University

BS, Mathematics & Computer Science (double major) · Advisor: Persi Diaconis

Selected Publications

637+ citations

Programming contests, competitive programming curricula, and how everybody benefits

Guha, A., Lim, Y., Reed, B., Jaromczyk, J. W., & Vouga, E.

The Journal of Competitive Learning, 1(1) · 2025

Accurate data race prediction in the Linux kernel through sparse Fourier learning

Ryan, G., Cetin, B., Lim, Y., & Jana, S.

Proceedings of the ACM on Programming Languages, 8 (OOPSLA1), 810–832 · 2024

Competitive rumor spread in social networks

Lim, Y., Ozdaglar, A., & Teytelboym, A.

ACM SIGMETRICS Performance Evaluation Review, 44(3), 7–14 · 2017

Object bank: An object-level image representation for high-level visual recognition

Li, L.-J., Su, H., Lim, Y., & Fei-Fei, L.

International Journal of Computer Vision, 107(1), 20–39 · 2014

Full record: Publications · Google Scholar