research @openai | PhD @uwcse @uwnlp

Joined November 2019
We created SuperBPE🚀, a *superword* tokenizer that includes tokens spanning multiple words. When pretraining at 8B scale, SuperBPE models consistently outperform the BPE baseline on 30 downstream tasks (+8% MMLU), while also being 27% more efficient at inference time.🧵
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"In a hole in the ground, there lived a hobbit." BPE spends 13 tokens on this line, 7 of them on "in", "a", "the" and punctuation. CoBPE attaches those to their words: 6 tokens, same text. Across English: 30% shorter sequences, better LLMs at the same compute. #COLM2026 🧵
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Alisa Liu retweeted
Didn't expect to see LEGATO in the GPT-6 report 🤯🎼 GPT-6 Astra cites our work — and even uses the LEGATO camera subset for its OMR eval. We’ve since pushed it further with LEGATO 2: arxiv.org/abs/2607.05769
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Motif 3 is using a SuperBPE tokenizer! Very happy to see that superwords are boosting encoding efficiency (=> inference speed) in Korean as well as important domains like math and code!
Motif 3 is officially here. Today, we’re releasing Motif 3 Base and Motif 3. Motif 3 Base is our pretrained foundation model, while Motif 3 is built on top of it with post-training using NVIDIA NeMo-RL. Both models were developed with the support of Korea's Ministry of Science and trained on NVIDIA B200 GPUs. With Motif 3, we’re taking our first step into the frontier LLM race. There’s still a long way to go, but we believe we’ve built a model that deserves to be in the race. We’ve shared the details in our technical report and blog post. In collaboration with NVIDIA, we’re also releasing an NVFP4 version of Motif 3. All models will be available on Hugging Face. Links are in the comments.
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Alisa Liu retweeted
super excited to finally get this out. it’s the best model in the world for computer use and any professional workflow, and it’s just generally brilliant, fast, diligent, and it has high taste now! I was shamefully not too agi pilled in that I often did some work myself, but it completely changed since we started dogfooding 5.6 internally. Extremely capable, with little hand holding, and it constantly found issues in its own training/eval. it’s gonna be even more difficult to find some work that our model can’t help with me i guess :’)
Replying to @OpenAI
On the Artificial Analysis Coding Agent Index, GPT‑5.6 Sol sets a new state of the art at 80.0—2.8 points above Claude Fable 5—while using less than half the output tokens, taking less than half the time, and costing about one-third less.
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Alisa Liu retweeted
Replying to @charles_irl
@alisawuffles already fixed tokenizers. i just wish more models would adopt it :( arxiv.org/abs/2503.13423 but totally agree with your post. companies willing to do post-training can see a lot of gains here
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I'm joining OpenAI next week!🥹 The job search turned out to be really challenging but also super rewarding, so I wrote a small blog to share what I learned along the way and hopefully make the process a little less mysterious for the next person. alisawuffles.github.io/blog/…
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Alisa Liu retweeted
Introducing ><former Most transformers are rectangles◻️: every layer has the same width But is that optimal?🤔 We propose variable-width transformers that have different widths across layers, improving loss while cutting compute & KV cache size 🧵
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Alisa Liu retweeted
nice pre training work by nous claiming ~2.5x efficiency gains, building on previous research like MTP/SuperBPE. overall intuition is that at each step you want the model to process and predict more tokens
Today we release Token Superposition Training (TST), a modification to the standard LLM pretraining loop that produces a 2-3× wall-clock speedup at matched FLOPs without changing the model architecture, optimizer, tokenizer, or training data. During the first third of training, the model reads and predicts contiguous bags of tokens, averaging their embeddings on the input side and predicting the next bag with a modified cross-entropy on the output side. For the remainder of the run, it trains normally on next-token prediction. The inference-time model is identical to one produced by conventional pretraining. Validated at 270M, 600M, and 3B dense scales, and at 10B-A1B MoE. The work on TST was led by @bloc97_, @gigant_theo, and @theemozilla.
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In SuperBPE we found: as tokenizer compression increases, the compute-optimal ratio of train tokens to model params decreases — and remarkably, corresponds to the same underlying ratio of train *bytes* / param! Our new work makes it official: scaling laws depend on compression.
We present Compute Optimal Tokenization! 🔡 Common in LLM scaling works stick to one tokenizer, sweeping data/model size. But what happens when we control the tokenizer’s compression rate (bytes/token)? Here we sweep tokenizers, params, and data across compute budgets: [1/N]
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Follow the Flow was accepted to #ACL2026 main! 🎉 T2I models often struggle with text-image alignment issues. These are usually addressed at the diffusion stage. We offer a different POV: analyzing and intervening at the textual encoding. 📄 arxiv.org/abs/2504.01137
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It echoes findings in LLMs beyond T2I: Semantic Leakage in LMs (@hila_gonen) detokenization and token erasure (From tokens to words + @sheridan_feucht) model-internal "words" spanning multiple surface words (@alisawuffles, SuperBPE)
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Fast Byte Latent Transformer is accepted to ICML 2026! ⚡🥪 Byte-level LMs promise to free us from subword tokenizers, but decoding one byte at a time is super slow. We make BLT generation more efficient with BLT-D: text diffusion for parallel byte decoding. 1/
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We present Compute Optimal Tokenization! 🔡 Common in LLM scaling works stick to one tokenizer, sweeping data/model size. But what happens when we control the tokenizer’s compression rate (bytes/token)? Here we sweep tokenizers, params, and data across compute budgets: [1/N]
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Anthropic says Opus 4.7 uses “1.0-1.35x more tokens.” My quick measurements: Python / TOML / JSONL / structured data: ~1.20-1.30x English / Dutch prose: ~1.4-1.5x Korean prose: basically unchanged, though Korean was already poor on 4.6
The 4.7 tokenizer treats whitespace as separate tokens? A string consisting of 50 one-token words separated by Whitespace tokenizes to ~50 more tokens than with the 4.6 tokenizer. If so, the 1.35x more token estimate seems way too low.
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1/ "New tokenizer" does not imply "new base model," and "new base model" is not the simplest explanation. There are much simpler explanations that fit Anthropic's public description of Opus 4.7 equally well.
Opus 4.7 has a new tokenizer. This means it's also a new base model. Glory days of pretraining still very much going.
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4/ Zheng et al. 2025 ("Broken Tokens") showed that non-canonical tokenizations at inference time can improve instruction-tuned model performance. E.g., character-level tokenization improves string manipulation and code understanding tasks. arxiv.org/abs/2506.19004
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Wow the first time Olmo is top is for LEAST DEPRESSED that's a huge win. Go team. Happy models make happy users.
Replying to @anna_soligo
The setup: ask a model a question, then repeatedly tell it the answer is wrong. By turn 8, over 70% of Gemma-27B responses hit our "high frustration" threshold. So do 27% of responses from Gemini Flash. Claude, GPT, Grok, Qwen, and OLMo: all under 1%.
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Alisa Liu retweeted
Introducing Olmo Hybrid, a 7B fully open model combining transformer and linear RNN layers. It decisively outperforms Olmo 3 7B across evals, w/ new theory & scaling experiments explaining why. 🧵
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📢 Life update 📢 After a wonderful time at @allen_ai, I've joined @CisLmu at @LMU_Muenchen as a tenure-track assistant professor in NLP. Thrilled to be back in Europe and to start a lab in Munich's flourishing AI ecosystem! 🎉
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Alisa Liu retweeted
I would like to buy RL data! Please pitch me on your rl data company. Budget is $100s of k, not millions. And we will release the data publicly! Email is finbarrt @ my employer’s website.
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