What fifteen years in the ICPC changed about how I solve problems
Reflections across competing, coaching, judging, organizing, and teaching—and what those roles reveal about the real work of problem solving.
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Production AI · Architecture · Reliability
Reliable AI systems, built for the real world.
I’m Christian Yongwhan Lim. I help teams turn ambitious AI products into dependable systems through architecture, evaluation, observability, and recovery.
Chief Architect at Probook · Adjunct at Columbia · Director of Internships at the ICPC Foundation. Formerly Google Research and Two Sigma.
New York, 2026
Current proof · September 2026
Explore the work →
- AI evaluation Reproducible persona and voice measurement
- ITCS 2027 Cascade-centrality paper submitted
- 20 chapters Advanced programming text in classroom use
How I can help
Start with the problem in front of you
01 · Primary
Make a production AI system dependable
Architecture, evaluation, observability, workflow state, latency, and recovery across the full system—not only the model.
Discuss the system → 02 · LearningBuild a technical-learning environment
Curriculum, deliberate practice, coaching, feedback loops, mentorship, and durable community leadership.
Compare approaches → 03 · CollaborationBring the work into a room
Speaking and substantive collaboration on AI reliability, engineering leadership, problem solving, and technical education.
Explore a fit →“He has had a bigger impact in that short time than almost anyone has had in the history of North America.”
Selected work
View all selected work →
A few things that define the body of work
01 / Evaluation
02 / Research
03 / Reliability
Measuring persona reliability
A reproducible, multi-model evaluation program for identity, voice, conversational continuity, and drift—shared at a deliberately public-safe level.
80/80 reproducibility checks · honest baselines · calibrated operating guidance Explore the public overview →Cascade centrality
Hardness, approximation, structural laws, and network augmentation supported by exact computation.
ITCS 2027 submitted · two focused manuscripts in preparationSee the research program →Contest engineering
Adversarial validation and release discipline for high-stakes programming contests.
17-problem regional draft · automated checks + human sign-offSee the engineering approach →Working Notes
How I review an ICPC contest with a team
The scoreboard records outcomes. A useful review reconstructs the decisions, failure modes, and team interactions that produced them.
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