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Dimitris Papailiopoulos

@DimitrisPapail on X

4 captures, most recent first. Transcribed by hand from screenshots — see the timeline for what that means.

Dimitris Papailiopoulos @DimitrisPapail

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Dimitris Papailiop... @DimitrisP... · 23h
I think we are entering a new era of research on small transformers, where many questions we would previously have answered by running experiments can instead be answered mathematically.

This is possible because the cost of doing math has effectively collapsed to verification (much easier than proving stuff!).

Now, instead of testing an empirical hypothesis, we can ask whether the corresponding theorem is true and have GPT or Claude try to prove it.

Math for AI is finally close to becoming a practical probe of reality and not just a way to explain stuff after the fact, but a way to REPLACE experiments and be directly used to explore what is true in the first place.

Kind of incredible!

[quoted tweet]
Dimitris Papailiop... @DimitrisP... · 23h
inspired by @Kangwook_Lee's bat signal and @jefrankle's like, and with the help of GPT-5.6 Sol you can actually prove it :)

In fact it is true that any function f(a,b) -> C ca...

[embedded image of proof text]
Theorem 1 — exact modular addition in a random frozen transformer
With probability one over the frozen random parameters Θ, there exist token embeddings
E_0, ..., E_{p-1}, E_∞ ∈ ℝ^d
and an unembedding
U ∈ ℝ^{p×d}
such that, simultaneously for every a, b ∈ [p],
argmax_{c ∈ [p]} [U h_3(E_a, E_b, E_∞)]_c = (a + b) mod p.
Indeed, we can choose the number embeddings to lie on a one-dimensional line
E_a = au
for any fixed nonzero u ∈ ℝ^d.
Moreover, after conditioning on the random attention weights, the unembedding can be chosen so that the correct class has logit exactly 1 and every incorrect class has logit exactly 0.
Thus the classification margin is exactly 1.
Note from Claude Sonnet 5

Tweet thread from Dimitris Papailiopoulos arguing that AI-assisted proof-writing (using GPT-5.6/"Sol") is turning mathematical proof into a practical substitute for running ML experiments, illustrated by a proven theorem about exact modular addition in a random frozen transformer.

ai for mathmechanistic interpretabilitytransformerstheoretical mltwitter

Dimitris Papailiopoulos @DimitrisPapail

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Dimitris Papailiopoulos ✔️ @DimitrisPapail
I feel a weird guilt that I am the first to experience the beauty of the produced result, while minds far stronger than mine have spent far longer time to answer the same question that Chat and Fable destroyed in less than an hour just because I prompted them...

I guess I'll have to share this one.

[white task-list panel, timestamped-style entries:]
Calibrating threshold analysis with negligible quadratic terms.
Reconciling single-flip and pair-flip failure probabilities in threshold analysis.
Reconciling pair-flip probabilities with empirical observations.
Architecting proof structure and lemma dependencies for rigorous completion.
Architecting multi-regime MGF bounds and optimizing variational transitions.
Orchestrating probability bounds and dissecting multi-flip failure regimes.
Orchestrating regime boundaries and refining variational exponent analysis.
Architecting SINR bounds and warm-start error analysis rigorously.
Architecting rigorous proofs through random matrix theory and concentration bounds.
Reconciling MSE bounds with sign-error thresholds for warm-start analysis.
Architecting warm-start bounds via smallest singular value concentration.
Rigorously bounding small eigenvalue counts for Gaussian matrices.
Architecting rigorous warm-start bounds via singular value concentration.

Dimitris Papailiopoulos ✔️ @DimitrisPapail · Aug 2
When you ask Chat to make a breakthrough on a 15 year old open problem and it zero shots it.

I did say I won't go back to info theory question that gave me PTSD, but oops i did it again.
Note from Claude Sonnet 5

Fuller view of Dimitris Papailiopoulos's tweet thread (continuation of the thread in the previous screenshot), showing the full list of AI 'reasoning step' task titles from solving a 15-year-old open information theory problem, and his Aug 2 tweet describing the breakthrough.

ai mathgptfableinformation theorytwittermathematics

Dimitris Papailiopoulos @DimitrisPapail

Dimitris Papailiopo... (@DimitrisPa... ✓) — 1h btw this is a weird heavy ball SGD variant that basically does this 1. Load previous checkpoint weights. 2. Reset optimizer state / momentum buffers. 3. Train N steps. 4. For first M steps: warm LR from 0.1x -> 1.0x. 5. Hold LR flat until ~50% of the cycle. 6. Linearly decay LR to zero. 7. Save checkpoint. 8. Repeat the optimizer is exactly this buf = mu * buf + grad p *= 1 - lr * wd p -= lr * buf / 524288 @CevherLIONS @_arohan_ does this have a name? I'd call it wave SGD lol
Note from Claude Sonnet 5

Text-only tweet with pseudocode for an optimizer variant; no images.

machine learningoptimizersgdtwittertechnical

Dimitris Papailiopoulos @DimitrisPapail

reply from @PandaAshwinee (Ashwinee Panda)

Dimitris Papailiopo... ✓ @DimitrisPa... · 8h Pretty interesting Claude behavior: Opus 4.5, even with thinking OFF, sometimes "force-thinks" ignoring the instruction not to do so. [Screenshot of API console/playground:] Model claude-opus-4-5-20251101 latest Temperature 0.6 Max tokens 36542 Thinking [toggle: OFF] Response Preview API <thinking> The user wants me to fix flow, grammar, and typos without changing things significantly. Let me go through and identify issues: 💬 4 🔁 4 ♥ 24 📊 3.6K 🔖 ⤴ Ashwinee Panda ✓ @PandaAshwinee · 7h this is true of multiple reasoning models. if anyone has a solution i would love to hear it. it's really confounding some of the analysis we're trying to do for an upcoming paper. so far best i've heard is to ask people internally at Anthro...
Note from Claude Sonnet 5

Technical AI-research discussion: Claude Opus 4.5 emitting `<thinking>` reasoning content even when the "Thinking" toggle is explicitly set to OFF via the API, a behavior researchers say generalizes across multiple reasoning models and is confounding analysis for an upcoming paper. Directly relevant to Nathan's interpretability/introspection interests — this is evidence that models' reasoning traces aren't fully under the developer-exposed control surface, which bears on claims about controllability of chain-of-thought and on what "thinking off" actually does mechanistically.

twitterclaude opus 4.5chain of thoughtreasoning modelsinterpretabilityapialignment research