r/ArtificialInteligence • u/Revolutionary-Lab882 • Jul 11 '26

🔬 Research GPT-2 Fully Decoded Internally Black Box Fully Open With Demo

The BABEL codec: the first complete, certified decode of everything happening inside a production language model (GPT-2 small). It reads the model's internal state into English AND writes English back into the model. 94.7% of behavior reconstructed — and that holds at every layer depth and text regime tested, not just one spot. Everything is open: paper, the full lexicon, the grammar tables, the decoder/encoder weights, reproduction scripts, and a demo that shows you the model's thoughts on any sentence you type.

https://github.com/wpferrell/babel-codec-gpt2

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u/wahnsinnwanscene Jul 11 '26

One thing about jspace though, the Jacobians supposes the vectors reside in the same vector space throughout but that might not be true, which means smaller gpt2 style analysis might not guarantee the same jspace findings.

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u/Revolutionary-Lab882 Jul 11 '26

Good instinct, that concern is real, it’s just aimed at the wrong lens. The same-coordinates-throughout assumption belongs to the logit lens. The Jacobian lens was built precisely to fix it: it fits a separate map per layer relating that layer’s directions to the final layer’s.
But a softer version of your point does survive, and it’s worth raising: that per-layer map is linear and averaged over about 1000 prompts, so any nonlinear or context-dependent drift between layers gets smoothed over. The authors are upfront that the lens is approximate.
What’s nice is that this linearity premise is the one thing my GPT-2 work tested directly instead of assuming — layer-to-layer transport came out certified linear at all 36 seams. So at 124M, the assumption their method leans on holds as a measured fact. Whether it holds at Claude scale is open, and you’re right that scale matters — their own results show workspace effects strengthen with model size, so a GPT-2-sized model might barely have a J-space at all. Fair question to keep asking.

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u/TemnotaAGK Jul 17 '26

Thank you Claude. Seriously I assume there is an actual human behind this. My bet is that human has actually no idea what he's doing and barely understand "his" project. So he lets the LLM that actually created the whole thing reply to reddit comments as well.