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12 essays
Face Search Works Because It Throws Your Face Away
Computer Science Artificial Intelligence & Data

Face Search Works Because It Throws Your Face Away

Every facial recognition match you've ever seen was never the closest possible match — it was the fastest good-enough guess a system built to discard information could produce. That design choice, not just biased photos, explains why it fails some faces more than others.

S.J. Nam, Ph.D Jul 6, 2026 8 min read
Chunking Isn't the RAG Bottleneck Everyone Blames It For
Computer Science Artificial Intelligence & Data

Chunking Isn't the RAG Bottleneck Everyone Blames It For

Every RAG tutorial insists that smarter, semantic text-splitting is the key to good retrieval. The data says otherwise — and points to two duller fixes that actually work.

S.J. Nam, Ph.D Jul 5, 2026 7 min read
Search Was Never About Speed — It Was About Never Reading At All
Computer Science Databases & Information Systems

Search Was Never About Speed — It Was About Never Reading At All

Google-scale search feels like a triumph of server farms and fiber. It isn't. The real trick — refusing to ever read a document at query time — was invented on machines with less memory than a phone photo.

S.J. Nam, Ph.D Jul 5, 2026 8 min read
Hybrid Search Doesn't End the Tuning Problem, It Just Hides It
Computer Science Databases & Information Systems

Hybrid Search Doesn't End the Tuning Problem, It Just Hides It

A license plate that vector search couldn't find became the industry's favorite parable for hybrid search. The part of the story usually left out: the 'no-tuning' fusion method everyone defaults to has a documented accuracy discount nobody checks for.

S.J. Nam, Ph.D Jul 2, 2026 8 min read
The Ruler That Measures Nothing Fixed
Computer Science Artificial Intelligence & Data

The Ruler That Measures Nothing Fixed

Every chatbot that says 'here's the most relevant passage' is quietly lying about how it found it — the math underneath is a stack of approximations, not a fact about meaning.

S.J. Nam, Ph.D Jul 2, 2026 7 min read
Word2vec's King-Queen Trick Only Works Because the Answer Was Rigged
Computer Science Artificial Intelligence & Data

Word2vec's King-Queen Trick Only Works Because the Answer Was Rigged

The most famous four-word equation in AI didn't prove machines grasp gender and royalty — it worked because researchers quietly barred the one answer that would have broken it.

S.J. Nam, Ph.D Jun 28, 2026 6 min read
Your Recommendations Aren't About You, They're About the Crowd
Computer Science Artificial Intelligence & Data

Your Recommendations Aren't About You, They're About the Crowd

Every 'personalized' recommendation you get is shaped by a geometric quirk called hubness—a mathematical law that quietly funnels everyone toward the same small set of popular items, no matter how much data the system has on you.

S.J. Nam, Ph.D Jun 27, 2026 8 min read
Meaning Isn't a Place in the Model — It's a Ruler You Chose
Computer Science Artificial Intelligence & Data

Meaning Isn't a Place in the Model — It's a Ruler You Chose

Ask an AI model how similar tulips are to a recession and you get a suspiciously high score. That glitch exposes a quiet, load-bearing choice hiding inside every claim that meaning 'lives' in a direction.

S.J. Nam, Ph.D Jun 25, 2026 8 min read
AI Search Engines Cite Sources That Don't Say What They Claim
Computer Science Artificial Intelligence & Data

AI Search Engines Cite Sources That Don't Say What They Claim

Those tidy footnotes under an AI search answer look like scholarship. Columbia researchers found they're often just theater — real links attached to claims the sources never made.

S.J. Nam, Ph.D Jun 23, 2026 7 min read
RAG Doesn't Make AI Smarter, It Makes AI Citable
Computer Science Artificial Intelligence & Data

RAG Doesn't Make AI Smarter, It Makes AI Citable

Retrieval-Augmented Generation was sold as a cure for AI hallucination. It's actually something narrower and stranger: a way to give confident machines a paper trail — one that can be wrong and still look convincing.

S.J. Nam, Ph.D Jun 21, 2026 8 min read
Cosine Similarity Was Built for Card Catalogs, Not Meaning
Computer Science Artificial Intelligence & Data

Cosine Similarity Was Built for Card Catalogs, Not Meaning

That tidy 0.91 similarity score your AI system just spat out isn't measuring meaning — it's inheriting a length-correction hack from 1970s library search software, and a recent study shows the inheritance comes with a hidden crack.

S.J. Nam, Ph.D Jun 20, 2026 7 min read
Embeddings Were Never a One-Way Street
Computer Science Cybersecurity

Embeddings Were Never a One-Way Street

The industry sold vector embeddings as a privacy-safe stand-in for raw text. A reconstruction algorithm called Vec2Text just proved that the 'anonymized' fingerprint can be lifted, matched, and read back word for word.

S.J. Nam, Ph.D Jun 18, 2026 7 min read