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Joshua Engels

9 accepted papers

2025

Are Sparse Autoencoders Useful? A Case Study in Sparse Probing

ICML 2025poster

Sparse autoencoders (SAEs) are a popular method for interpreting concepts represented in large language model (LLM) activations. However, there is a lack of evidence regarding the validity of their interpretations due to the lack of a ground truth for the concepts used by an LLM, and a growing numbe…

2025

Dense SAE Latents Are Features, Not Bugs

NeurIPS 2025poster

Sparse autoencoders (SAEs) are designed to extract interpretable features from language models by enforcing a sparsity constraint. Ideally, training an SAE would yield latents that are both sparse and semantically meaningful. However, many SAE latents activate frequently (i.e., are *dense*), raising…

Cited by 0SourceScholar
2025

Efficient Dictionary Learning with Switch Sparse Autoencoders

ICLR 2025poster

Sparse autoencoders (SAEs) are a recent technique for decomposing neural network activations into human-interpretable features. However, in order for SAEs to identify all features represented in frontier models, it will be necessary to scale them up to very high width, posing a computational challen…

2025

Not All Language Model Features Are One-Dimensionally Linear

ICLR 2025poster

Recent work has proposed that language models perform computation by manipulating one-dimensional representations of concepts ("features") in activation space. In contrast, we explore whether some language model representations may be inherently multi-dimensional. We begin by developing a rigorous d…

Cited by 0SourcePDFScholar
2024

Approximate Nearest Neighbor Search with Window Filters

ICML 2024poster

We define and investigate the problem of *c-approximate window search*: approximate nearest neighbor search where each point in the dataset has a numeric label, and the goal is to find nearest neighbors to queries within arbitrary label ranges. Many semantic search problems, such as image and docume…

2023

DESSERT: An Efficient Algorithm for Vector Set Search with Vector Set Queries

NeurIPS 2023poster

We study the problem of $\text{\emph{vector set search}}$ with $\text{\emph{vector set queries}}$. This task is analogous to traditional near-neighbor search, with the exception that both the query and each element in the collection are $\text{\textit{sets}}$ of vectors. We identify this problem as…