Stochastic Estimation of Transduced Language Models
Paper Guide Brief
Reading Brief
This paper introduces an unbiased stochastic estimator for transduced language models (TLMs), which compose a pretrained source language model with a finite-state transducer. The authors replace the threshold-pruned beam summing of prior work with sampling without replacement and Horvitz–Thompson reweighting, providing an unbiased estimator of target prefix probabilities with almost-sure halting guarantees. They evaluate on encyclopedic text and DNA-to-amino-acid transductions, showing better compute-variance tradeoffs than sequential Monte Carlo baselines and making long-target estimation feasible, while also demonstrating that replacing biased pruning in a published reading-time analysis changes the estimated surprisal but not the conclusions. The work is primarily a contribution to probabilistic inference and estimation methods for language models, situated within statistical NLP and probabilistic AI, with applications in computational linguistics and deep learning.
Central Claim
A new unbiased estimator for transduced language model prefix probabilities, replacing threshold-pruned beam summing with sampling without replacement and Horvitz–Thompson reweighting, with almost-sure halting guarantees and adaptive particle budgets.
Contribution
A new unbiased estimator for transduced language model prefix probabilities, replacing threshold-pruned beam summing with sampling without replacement and Horvitz–Thompson reweighting, with almost-sure halting guarantees and adaptive particle budgets.
Why It Matters
This contribution matters because it replaces the unknown error of threshold-pruned beam summing with a provably unbiased estimator, enabling reliable estimation of target prefix probabilities in settings where prior methods are either biased or computationally infeasible.
Prerequisites
transduced language models, sampling without replacement, Horvitz-Thompson reweighting, beam summing, sequential Monte Carlo
Atlas Placement
Natural Language Processing (subfield)
Read If
You care about transduced language models, sampling without replacement, Horvitz-Thompson reweighting.
Skip If
You only care about compute-variance tradeoff, relative root-mean-square error.
Noosaga Placements
- The paper directly addresses language model estimation, specifically transduced language models that compose pretrained source language models with transducers, and evaluates on text and DNA language modeling tasks.Transduced language models (TLMs) compose a pretrained source language model with a functional finite-state transducer to induce a language model over target strings.We evaluate the method on encyclopedic text and DNA against sequential Monte Carlo baselines that resample with replacement.
- Statistical NLPframework90%The paper is situated within statistical NLP, as it deals with probabilistic language models, estimation of probabilities, and statistical inference methods like sampling and reweighting.Transduced language models (TLMs) compose a pretrained source language model with a functional finite-state transducer to induce a language model over target strings.We show that applying this correction recursively gives an unbiased estimator of the target prefix probability and lets us estimate the mass lost by threshold pruning.
- The core contribution is a stochastic estimation method with unbiasedness guarantees, using sampling without replacement, Horvitz-Thompson reweighting, and sequential Monte Carlo, which are probabilistic inference techniques.Instead, we resample source prefixes without replacement and reweight each selected prefix by the inverse of its inclusion probability.We show that applying this correction recursively gives an unbiased estimator of the target prefix probability and lets us estimate the mass lost by threshold pruning.
- Approximate Inferenceframework85%The paper directly uses approximate inference techniques, specifically sampling without replacement and sequential Monte Carlo, to estimate intractable sums over source strings.Instead, we resample source prefixes without replacement and reweight each selected prefix by the inverse of its inclusion probability.We evaluate the method on encyclopedic text and DNA against sequential Monte Carlo baselines that resample with replacement.
- The paper applies the method to a psycholinguistic reading-time analysis, computing word-level surprisal for reading-time prediction, which is a computational linguistics application.Replacing threshold pruning with unbiased sampling in a published reading-time analysis substantially lowers the estimated corpus surprisal but leaves the published conclusions unchanged.In psycholinguistics, Kiegeland et al. (2026) use a TLM to derive word-level surprisal from a token-level language model for reading-time prediction.
- Neural NLPframework70%The paper deals with neural language models (e.g., GPT-2) as source models in transduced language models, and the method is applied to improve estimation for these models.We also run fptb with GPT-2 large, pgpt2 (Radford et al., 2019).On pgpt2 ◦ fptb , beam_swor_adaptive at nominal M =200 takes 772 seconds, compared with 1224 seconds for beam_summing with pruneτ .
- The method is applied to pretrained neural language models like GPT-2, and the paper discusses source models that are autoregressive neural networks, though the core contribution is not about deep learning architectures.We also run fptb with GPT-2 large, pgpt2 (Radford et al., 2019).On pgpt2 ◦ fptb , beam_swor_adaptive at nominal M =200 takes 772 seconds, compared with 1224 seconds for beam_summing with pruneτ .
- Neural and Deep Learning Approachesframework60%The paper applies the method to a computational linguistics task (reading-time prediction) and uses language models, which are central to neural and deep learning approaches in computational linguistics.Replacing threshold pruning with unbiased sampling in a published reading-time analysis substantially lowers the estimated corpus surprisal but leaves the published conclusions unchanged.In psycholinguistics, Kiegeland et al. (2026) use a TLM to derive word-level surprisal from a token-level language model for reading-time prediction.
- The paper involves estimation theory, variance reduction, and compute-variance tradeoffs, which are machine learning concerns, though the focus is on probabilistic estimation rather than learning algorithms.It achieves a better compute–variance tradeoff on text and lower error at the same maximum number of particles on DNA.The resulting estimator is unbiased and replaces unknown pruning error with sampling variance.
Abstract
Transduced language models (TLMs) compose a pretrained \emph{source} language model with a functional finite-state transducer to induce a language model over \emph{target} strings. Computing the probability of a target prefix under a TLM amounts to summing the source-model probabilities of all source strings that the transducer maps to target strings beginning with that prefix. This set can be exponentially large or infinite. Prior work uses a computational shortcut based on source prefix probabilities, then approximates the resulting sum with threshold-pruned beam summing. This produces a lower bound with unknown error. Instead, we resample source prefixes without replacement and reweight each selected prefix by the inverse of its inclusion probability. We show that applying this correction recursively gives an unbiased estimator of the target prefix probability and lets us estimate the mass lost by threshold pruning. Our beam-summing algorithm extends the retained source prefixes and samples which prefixes to keep, reducing their number as more probability mass is added to the running estimate. This can save computation and guarantees that the run halts with probability one. We evaluate the method on encyclopedic text and DNA against sequential Monte Carlo baselines that resample with replacement. It achieves a better compute--variance tradeoff on text and lower error at the same maximum number of particles on DNA. On a DNA-to-amino-acid transduction, it reduces runtime by several orders of magnitude relative to threshold-pruned beam summing and makes estimating prefix probabilities for long target strings feasible. Replacing threshold pruning with unbiased sampling in a published reading-time analysis substantially lowers the estimated corpus surprisal but leaves the published conclusions unchanged.
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