Vaishnavh Nagarajan

@vaishnavh.bsky.social

Foundations of AI. I like simple and minimal examples and creative ideas. I also like thinking about the next token 🧮🧸 Google | PhD, CMU | https://arxiv.org/abs/2504.15266 | https://arxiv.org/abs/2403.06963 vaishnavh.github.io

In new post, I write about how we misunderstand the famous lottery ticket hypothesis. We tend to think that a network needs to be exponentially large for there to be a subnetwork to win the lottery. This is incorrect---a small network suffices! I use a dart throwing analogy to make sense of this.

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In my next blogpost, I write about how I view technical communication: it's like trying to communicate an escape route to someone without a map but with a catch: you're not with them. You only have a walkie-talkie. Also, they're in panic.

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Also, what's the catch with punishing bad reviews by preventing future submissions? Say: if your reviews are egregiously bad as flagged by multiple ACs across at least two conferences, you won't be able to submit papers to the next N conferences. (Possible that I'm missing something here.)

Vaishnavh Nagarajan@vaishnavh.bsky.social · 5mo ago

Curious why conferences don't have a system where the authors of every paper together guarantee N reviews per paper (and they can distribute the load amongst themselves). This way wouldn't we tax authors in proportion to the number of papers they burden the system with?

Curious why conferences don't have a system where the authors of every paper together guarantee N reviews per paper (and they can distribute the load amongst themselves). This way wouldn't we tax authors in proportion to the number of papers they burden the system with?

A recent paper (arxiv.org/abs/2602.18671) made me question something basic: do the logits of a language model model the next-token or the full sequence distribution? It really messed with my brain (in a fun way!). I wrote about the paper to clarify my thinking. vaishnavh.github.io/blog/joint-o...

What does a language model model? - Vaishnavh Nagarajan

TL;DR: Does the next-token logit track the conditional or the joint probability of the whole sequence?I had an invisi...

vaishnavh.github.io

The visual world is composed of objects, and those objects are composed of features. But do VLMs exploit this compositional structure when processing multi-object scenes? In our 🆒🆕 #ICLR2026 paper, we find they do – via emergent symbolic mechanisms for visual binding. 🧵👇

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in associative memory, the latent space doesn't really encode any interesting distance. imagine you're trying to store which countries share borders. you could simply write down a list of adjacent countries OR you could visualize the world map in your head. this is "associative" vs "geometric".

1/ We found that deep sequence models memorize atomic facts "geometrically" -- not as an associative lookup table as often imagined. This opens up practical questions on reasoning/memory/discovery, and also poses a theoretical "memorization puzzle."

If X, Y, Z are iid high-dim Gaussian N(0, I), what's the angle between X-Y and Z-Y? A. Concentrates at 90 deg B. Concentrates, NOT at 90° C. Doesn't concentrate anywhere. My (and most people's) instincts got this wrong! vaishnavh.github.io/blog/high-di...

Angles between high-dimensional vectors - Vaishnavh Nagarajan

Switch off your brain and answer this:Given three points $\mathbf{X}, \mathbf{Y}, \mathbf{Z}$ sampled from a high-dim...

vaishnavh.github.io

A string may get 17 times less probability if tokenised as two symbols (e.g., ⟨he, llo⟩) than as one (e.g., ⟨hello⟩)—by an LM trained from scratch in each situation! Our new ACL paper proposes an observational method to estimate this causal effect! Longer thread soon!

Title of paper "Causal Estimation of Tokenisation Bias" and schematic of how we define tokenisation bias, which is the causal effect we are interested in.

This paper is quite nice. It mixes some useful toy models of creativity with insights about how to induce more creativity in LLMs that are better than greedy sampling

Vaishnavh Nagarajan@vaishnavh.bsky.social · last yr.

📢 New #paper on creativity & multi-token prediction! We design minimal open-ended tasks to argue: → LLMs are limited in creativity as they learn to predict the next token → creativity can be improved via multi-token learning & injecting noise ("seed-conditioning" 🌱) 1/ #MLSky #AI #arxiv 🧵👇🏽

This isn't fake news. One of the craziest AI research papers I've been on in a while. Weird ablations on RLVR shows that the Qwen 2.5 models can learn with literally random rewards, likely due to some funkiness in mid-training and the GRPO setup.

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