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Posts by Tim Vieira

Merge transducers for a BPE tokenizer.

Merge transducers for a BPE tokenizer.

My paper "Tokenization as Finite-State Transduction" was accepted to Computational Linguistics.

This was my final PhD degree requirement :)

The goal was to unify the major tokenization algorithms under a finite-state automaton framework. For example, by encoding a BPE tokenizer as a transducer.

8 months ago 30 6 2 1

Many LM applications may be formulated as text generation conditional on some (Boolean) constraint.

Generate a…
- Python program that passes a test suite.
- PDDL plan that satisfies a goal.
- CoT trajectory that yields a positive reward.
The list goes on…

How can we efficiently satisfy these? 🧵👇

11 months ago 13 6 2 0
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Current KL estimation practices in RLHF can generate high variance and even negative values! We propose a provably better estimator that only takes a few lines of code to implement.🧵👇
w/ @xtimv.bsky.social and Ryan Cotterell
code: arxiv.org/pdf/2504.10637
paper: github.com/rycolab/kl-rb

11 months ago 7 3 1 0
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#ICLR2025 Oral

How can we control LMs using diverse signals such as static analyses, test cases, and simulations?

In our paper “Syntactic and Semantic Control of Large Language Models via Sequential Monte Carlo” (w/ @benlipkin.bsky.social,
@alexlew.bsky.social, @xtimv.bsky.social) we:

11 months ago 7 6 1 0
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New preprint on controlled generation from LMs!

I'll be presenting at NENLP tomorrow 12:50-2:00pm

Longer thread coming soon :)

1 year ago 20 9 1 0
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Tokenization is an often-overlooked aspect of modern #NLP, but it’s experiencing a resurgence — thanks in large part to @karpathy.bsky.social and his classic tweet:

x.com/karpathy/sta...

Come hang out with us and let's fix these problems!

1 year ago 7 1 0 0
Join the Token ##ization Discord Server! Check out the Token ##ization community on Discord - hang out with 24 other members and enjoy free voice and text chat.

Today we are launching a server dedicated to Tokenization research! Come join us!

discord.gg/CDJhnSvU

1 year ago 18 6 3 3
Also note that, instead of adding KL penalty in the reward, GRPO regularizes by directly adding the KL divergence between the trained policy and the reference policy to the loss, avoiding complicating the calculation of the advantage.

Also note that, instead of adding KL penalty in the reward, GRPO regularizes by directly adding the KL divergence between the trained policy and the reference policy to the loss, avoiding complicating the calculation of the advantage.

@xtimv.bsky.social and I were just discussing this interesting comment in the DeepSeek paper introducing GRPO: a different way of setting up the KL loss.

It's a little hard to reason about what this does to the objective. 1/

1 year ago 49 9 3 0

I made a starter pack for people in NLP working in the area of tokenization. Let me know if you'd like to be added

go.bsky.app/8P9ftjL

1 year ago 12 5 0 0
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It's ready! 💫

A new blog post in which I list of all the tools and apps I've been using for work, plus all my opinions about them.

maria-antoniak.github.io/2024/12/30/o...

Featuring @kagi.com, @warp.dev, @paperpile.bsky.social, @are.na, Fantastical, @obsidian.md, Claude, and more.

1 year ago 215 25 36 4

No amazing live music at the closing ceremony...

1 year ago 1 0 0 0

Also, what will the role of adaptive/amortized inference be?

E.g., twisted SMC
arxiv.org/abs/2404.17546

Variational best-of-N
Our version:
arxiv.org/abs/2407.06057
Google's: arxiv.org/abs/2407.14622

1 year ago 1 0 0 0

What will the hardware-friendly search algorithms be? My top picks are best-of-N and sequential Monte Carlo because they do search without backtracking.

1 year ago 1 0 1 0
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hi everyone!! let's try this optimal transport again 🙃

1 year ago 329 31 2 0

Also: you can also use variables (or expressions?!) for the formatting information! #Python is cool...
More details and explanation at fstring.help

1 year ago 36 6 2 2

Bravo!

1 year ago 0 0 0 0
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Very close!

1 year ago 3 0 1 0

Surprisal of title beginning with 'O'? 3.22
Surprisal of 'o' following 'Treatment '? 0.11
Surprisal that title includes surprisal of each title character? Priceless [...I did not know titles could do this]

1 year ago 10 2 2 0
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Happy to share our work "Counterfactual Generation from Language Models" with @AnejSvete, @vesteinns, and Ryan Cotterell! We tackle generating true counterfactual strings from LMs after interventions and introduce a simple algorithm for it. (1/7) arxiv.org/pdf/2411.07180

1 year ago 14 3 2 0
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Variational approximation with Gaussian mixtures is looking cute! So here it's just gradient descent on K(q||p) for optimising the mixtures means & covariances & weights...
@lacerbi.bsky.social

1 year ago 33 7 2 0
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Gaussian approximation of a target distribution: mean-field versus full-covariance! Below shows a simple gradient descent on KL(q||p)

1 year ago 62 5 3 2