Transducing Language Models

Transducing Language Models

🎙 Vésteinn Snæbjarnarson 👥 3K 📅 August 31, 2026 ⏱ 40 min 👁 0 📄 original study 🧭 2026-08-31
Available in: English (current) Français

Keywords

transductionlanguage modelstokenizationpushforwardfinite-state transducers

Summary

The talk presents a method to convert a language model defined over one tokenization (e.g., subword tokens) into a language model over another tokenization (e.g., words, bytes, amino acids) without retraining. The core idea is to use a finite-state transducer to map between tokenizations and to compute the target distribution via a pushforward measure. The speaker defines key concepts such as prefix probabilities and pre-cover sets, and derives a decomposition that allows computing target prefix probabilities using only source prefix probabilities and a finite set of string probabilities. An algorithm is presented to enumerate quotient and remainder elements of the pre-cover, implemented using finite-state automata. The method is applied to BPE-to-word, BPE-to-byte, and DNA-to-amino-acid conversions. The talk also discusses optimizations, including recursive computation and threshold pruning, and introduces a follow-up work on stochastic estimation to address bias from pruning.

139 words

Critical Evaluation

Value of the Information & Strength of the Argument

The talk provides a novel and theoretically grounded approach to a practical problem in NLP. The argumentation is clear and rigorous, building from definitions to a general decomposition theorem. The speaker motivates the problem with concrete examples (e.g., lowercasing, bad/good transducer) and demonstrates the complexity of the task. The value lies in offering a principled alternative to ad-hoc methods for comparing or using language models across tokenizations. The argumentation is solid, with a clear logical flow, though the presentation is dense and may require prior knowledge of automata theory.

Scientific Rigor, Source Quality, Title Accuracy

The talk is based on a peer-reviewed paper (ICER) and presents original research. The speaker cites prior work on converting subword models to byte-level models, but no specific sources are mentioned in the talk. The title accurately reflects the content. The presentation is scientifically rigorous, with formal definitions and proofs. However, the lack of explicit citations in the talk limits the ability to verify claims independently.

170 words

Title / Content Match

The title accurately reflects the content, which focuses on transducing (converting) language models between tokenizations.

Quality & Reliability

8/10

The talk presents a formal algorithmic framework with mathematical definitions, proofs of key decompositions, and experimental results. The speaker is a PhD student and the work is peer-reviewed (ICER). The presentation is rigorous, but the video lacks detailed experimental validation and external verification of claims.

Key Moments

Cited Sources

  • Paper: Transducing Language Models (ICER 2026) — The talk is based on this paper, presented at ICER.

Concurring Sources

  • Prior work on converting subword models to byte-level models — Mentioned in the talk as an extension, but no specific reference given.

Contribution & Novelties

The talk introduces a novel framework for converting language models between tokenizations without retraining, using finite-state transducers and a pushforward measure. This is a significant contribution as it enables direct comparison and use of models with different tokenizers, which is a common practical problem. The decomposition of target prefix probabilities into source prefix and string probabilities is a key theoretical insight. The follow-up work on stochastic estimation addresses the bias introduced by pruning, improving the practicality of the method.

Pour aller plus loin :

  • Finite-state transducer — Background on the mathematical model used for mapping between tokenizations.
  • Pushforward measure — The measure-theoretic concept underlying the probability transformation.
  • Byte pair encoding — The tokenization algorithm commonly used in language models, relevant to the BPE-to-word conversion.
  • Language model — General background on the models being transduced.

134 words

Radar Profile

The radar profile shows high scores in technical depth and information quality, reflecting the formal and rigorous nature of the talk. The lower score in information quantity is due to the limited scope of the presentation, which focuses on a specific method rather than a broad survey. The overall balance indicates a specialized, high-quality technical talk.

Reliability 8/10