Machine Learning System Design Interview, issue 18, Dec 4, 2025
The Semantic Imbalance Trap
Senior ML Engineer interview at OpenAI, and the interviewer asks:
βWe have 50 000 images of βcity streetsβ but only 45 images of βdeer at night.β How do we fix this ππ₯ππ¬π¬ ππ¦πππ₯ππ§ππ to prevent the model from ignoring the deer?β
Why rotating the same 45 deer wonβt save your classifier and how generative synthesis actually fixes class imbalance.
The full answer, with the mechanism and the arithmetic, is for paid subscribers on Substack.