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Thomas Hartvigsen

35 accepted papers

2026

BEDTime: A Unified Benchmark for Automatically Describing Time Series

ICML 2026poster

Recent works propose complex multi-modal models that handle both time series and language, ultimately claiming high performance on complex tasks like time series reasoning and cross-modal question answering. However, they skip foundational evaluations that such complex models should have mastered. S…

Cited by 0SourceScholar
2026

Estimating Semantic Alphabet Size for LLM Uncertainty Quantification

ICLR 2026poster

Many black-box techniques for quantifying the uncertainty of large language models (LLMs) rely on repeated LLM sampling, which can be computationally expensive. Therefore, practical applicability demands reliable estimation from few samples. Semantic entropy (SE) is a popular sample-based uncertaint…

Cited by 0SourceScholar
2026

Improving and Accelerating Offline RL in Large Discrete Action Spaces with Structured Policy Initialization

ICLR 2026poster

Reinforcement learning in combinatorial action spaces requires searching over exponentially many joint actions to simultaneously select multiple sub-actions that form coherent combinations. Existing approaches either simplify policy learning by assuming independence across sub-actions, which often y…

Cited by 0SourceScholar
2026

LLMs as Noisy Channels: A Shannon Perspective on Model Capacity and Scaling Laws

ICML 2026poster

Existing scaling laws for Large Language Models (LLMs), predominantly monotonic power laws, have successfully guided model development but fail to explain emerging non-monotonic phenomena such as catastrophic overtraining and quantization-induced degradation, where performance deteriorates despite i…

Cited by 0SourceScholar
2026

ReasonEdit: Editing Vision--Language Models using Human Reasoning

ICML 2026poster

Model editing aims to correct errors in large, pretrained models without altering unrelated behaviors. While some recent works have edited vision–language models (VLMs), no existing editors tackle reasoning-heavy tasks, which typically require humans and models to reason about images. We therefore p…

Cited by 0SourceScholar
2025

BalancEdit: Dynamically Balancing the Generality-Locality Trade-off in Multi-modal Model Editing

ICML 2025poster

Large multi-modal models inevitably decay over time as facts update and previously learned information becomes outdated. Traditional approaches such as fine-tuning are often impractical for updating these models due to their size and complexity. Instead, direct knowledge editing within the models pr…

2025

BraVE: Offline Reinforcement Learning for Discrete Combinatorial Action Spaces

NeurIPS 2025poster

Offline reinforcement learning in high-dimensional, discrete action spaces is challenging due to the exponential scaling of the joint action space with the number of sub-actions and the complexity of modeling sub-action dependencies. Existing methods either exhaustively evaluate the action space, ma…

Cited by 0SourceScholar
2025

Composable Interventions for Language Models

ICLR 2025poster

Test-time interventions for language models can enhance factual accuracy, mitigate harmful outputs, and improve model efficiency without costly retraining. But despite a flood of new methods, different types of interventions are largely developing independently. In practice, multiple interventions m…

2025

Constrained Discrete Diffusion

NeurIPS 2025poster

Discrete diffusion models are a class of generative models that construct sequences by progressively denoising samples from a categorical noise distribution. Beyond their rapidly growing ability to generate coherent natural language, these models present a new and important opportunity to enforce se…

Cited by 0SourceScholar
2025

Decoding the Rule Book: Extracting Hidden Moderation Criteria from Reddit Communities

EMNLP 2025

Effective content moderation systems require explicit classification criteria, yet online communities like subreddits often operate with diverse, implicit standards. This work introduces a novel approach to identify and extract these implicit criteria from historical moderation data using an interpr

Cited by 0SourcePDFScholar
2025

Efficient Knowledge Editing via Minimal Precomputation

ACL 2025short

Knowledge editing methods like MEMIT are able to make data and compute efficient updates of factual knowledge by using a single sentence to update facts and their consequences. However, what is often overlooked is a “precomputation step”, which requires a one-time but significant computational cost.…

Cited by 0SourcePDFScholar
2025

KScope: A Framework for Characterizing the Knowledge Status of Language Models

NeurIPS 2025poster

Characterizing a large language model's (LLM's) knowledge of a given question is challenging. As a result, prior work has primarily examined LLM behavior under knowledge conflicts, where the model's internal parametric memory contradicts information in the external context. However, this does not fu…

Cited by 0SourceScholar
2025

Learning under Temporal Label Noise

ICLR 2025poster

Many time series classification tasks, where labels vary over time, are affected by label noise that also varies over time. Such noise can cause label quality to improve, worsen, or periodically change over time. We first propose and formalize temporal label noise, an unstudied problem for sequentia…

Cited by 0SourcePDFScholar
2025

Lifelong Knowledge Editing requires Better Regularization

EMNLP 2025

Knowledge editing is a promising way to improve factuality in large language models, but recent studies have shown significant model degradation during sequential editing. In this paper, we formalize the popular locate-then-edit methods as a two-step fine-tuning process, allowing us to precisely ide

2025

Low-Bit Quantization Favors Undertrained LLMs

ACL 2025long

Low-bit quantization improves machine learning model efficiency but surprisingly favors undertrained large language models (LLMs). Larger models or those trained on fewer tokens exhibit less quantization-induced degradation (QiD), while smaller, well-trained models face significant performance losse…

Cited by 0SourcePDFScholar
2025

Math Neurosurgery: Isolating Language Models’ Math Reasoning Abilities Using Only Forward Passes

ACL 2025long

Math reasoning is an active area of Large Language Model (LLM) research because it is a hallmark of artificial intelligence and has implications in several domains, including math education. However, few works have explored how math reasoning is encoded within LLM parameters and if it is a skill tha…

2025

ModelCitizens: Representing Community Voices in Online Safety

EMNLP 2025

Automatic toxic language detection is important for creating safe, inclusive online spaces. However, it is a highly subjective task, with perceptions of toxic language shaped by community norms and lived experience. Existing toxicity detection models are typically trained on annotations that collaps

Cited by 0SourcePDFScholar
2025

Position: Medical Large Language Model Benchmarks Should Prioritize Construct Validity

ICML 2025oral

Medical large language models (LLMs) research often makes bold claims, from encoding clinical knowledge to reasoning like a physician. These claims are usually backed by evaluation on competitive benchmarks—a tradition inherited from mainstream machine learning. But how do we separate real progress…

Cited by 1SourcePDFScholar
2025

Sparse Autoencoder Features for Classifications and Transferability

EMNLP 2025

Sparse Autoencoders (SAEs) provide potential for uncovering structured, human-interpretable representations in Large Language Models (LLMs), making them a crucial tool for transparent and controllable AI systems. We systematically analyze SAE for interpretable feature extraction from LLMs in safety-

2025

WikiBigEdit: Understanding the Limits of Lifelong Knowledge Editing in LLMs

ICML 2025poster

Keeping large language models factually up-to-date is crucial for deployment, yet costly retraining remains a challenge. Knowledge editing offers a promising alternative, but methods are only tested on small-scale or synthetic edit benchmarks. In this work, we aim to bridge research into lifelong kn…

Cited by 0SourcePDFScholar
2024

Are Language Models Actually Useful for Time Series Forecasting?

NeurIPS 2024spotlight

Large language models (LLMs) are being applied to time series forecasting. But are language models actually useful for time series? In a series of ablation studies on three recent and popular LLM-based time series forecasting methods, we find that removing the LLM component or replacing it with a ba…

2024

BendVLM: Test-Time Debiasing of Vision-Language Embeddings

NeurIPS 2024poster

Vision-language (VL) embedding models have been shown to encode biases present in their training data, such as societal biases that prescribe negative characteristics to members of various racial and gender identities. Due to their wide-spread adoption for various tasks ranging from few-shot classif…

2024

Language Models Still Struggle to Zero-shot Reason about Time Series

EMNLP 2024finding

Time series are critical for decision-making in fields like finance and healthcare. Their importance has driven a recent influx of works passing time series into language models, leading to non-trivial forecasting on some datasets. But it remains unknown whether non-trivial forecasting implies that…

2024

Language Models are Surprisingly Fragile to Drug Names in Biomedical Benchmarks

EMNLP 2024finding

Medical knowledge is context-dependent and requires consistent reasoning across various natural language expressions of semantically equivalent phrases. This is particularly crucial for drug names, where patients often use brand names like Advil or Tylenol instead of their generic equivalents. To st…

2024

MATHWELL: Generating Educational Math Word Problems Using Teacher Annotations

EMNLP 2024finding

Math word problems are critical K-8 educational tools, but writing them is time consuming and requires extensive expertise. To be educational, problems must be solvable, have accurate answers, and, most importantly, be educationally appropriate. We propose that language models have potential to supp…

2024

TAXI: Evaluating Categorical Knowledge Editing for Language Models

ACL 2024findings

Humans rarely learn one fact in isolation. Instead, learning a new fact induces knowledge of other facts about the world. For example, in learning a korat is a type of cat, you also infer it is a mammal and has claws, ensuring your model of the world is consistent. Knowledge editing aims to inject n…

2024

UniTS: A Unified Multi-Task Time Series Model

NeurIPS 2024poster

Although pre-trained transformers and reprogrammed text-based LLMs have shown strong performance on time series tasks, the best-performing architectures vary widely across tasks, with most models narrowly focused on specific areas, such as time series forecasting. Unifying predictive and generative…

2023

Aging with GRACE: Lifelong Model Editing with Discrete Key-Value Adaptors

NeurIPS 2023poster

Deployed language models decay over time due to shifting inputs, changing user needs, or emergent world-knowledge gaps. When such problems are identified, we want to make targeted edits while avoiding expensive retraining. However, current model editors, which modify such behaviors of pre-trained mo…

2023

Encoding Time-Series Explanations through Self-Supervised Model Behavior Consistency

NeurIPS 2023spotlight

Interpreting time series models is uniquely challenging because it requires identifying both the location of time series signals that drive model predictions and their matching to an interpretable temporal pattern. While explainers from other modalities can be applied to time series, their inductive…

2023

Knowledge Amalgamation for Multi-Label Classification via Label Dependency Transfer

AAAI 2023technical

Multi-label classification (MLC), which assigns multiple labels to each instance, is crucial to domains from computer vision to text mining. Conventional methods for MLC require huge amounts of labeled data to capture complex dependencies between labels. However, such labeled datasets are expensive,…

2022

Recovering the Propensity Score from Biased Positive Unlabeled Data

AAAI 2022technical

Positive-Unlabeled (PU) learning methods train a classifier to distinguish between the positive and negative classes given only positive and unlabeled data. While traditional PU methods require the labeled positive samples to be an unbiased sample of the positive distribution, in practice the labele…

Cited by 23SourcePDFScholar
2022

ToxiGen: A Large-Scale Machine-Generated Dataset for Adversarial and Implicit Hate Speech Detection

ACL 2022long

Toxic language detection systems often falsely flag text that contains minority group mentions as toxic, as those groups are often the targets of online hate. Such over-reliance on spurious correlations also causes systems to struggle with detecting implicitly toxic language. To help mitigate these…

2021

Recurrent Bayesian Classifier Chains for Exact Multi-Label Classification

NeurIPS 2021poster

Exact multi-label classification is the task of assigning each datapoint a set of class labels such that the assigned set exactly matches the ground truth. Optimizing for exact multi-label classification is important in domains where missing a single label can be especially costly, such as in object…

2021

Semi-Supervised Knowledge Amalgamation for Sequence Classification

AAAI 2021technical

Sequence classification is essential for domains from medical diagnosis to online advertising. In these settings, data are typically proprietary, and annotations are expensive to acquire. Often times, so few annotations are available that training a robust model from scratch is impractical. Recently…