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Main Authors: Marcílio-Jr, Wilson E., Eler, Danilo M.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.23524
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author Marcílio-Jr, Wilson E.
Eler, Danilo M.
author_facet Marcílio-Jr, Wilson E.
Eler, Danilo M.
contents Sparse autoencoders (SAEs) trained on large language model activations output thousands of features that enable mapping to human-interpretable concepts. The current practice for analyzing these features primarily relies on inspecting top-activating examples, manually browsing individual features, or performing semantic search on interested concepts, which makes exploratory discovery of concepts difficult at scale. In this paper, we present Concept Explorer, a scalable interactive system for post-hoc exploration of SAE features that organizes concept explanations using hierarchical neighborhood embeddings. Our approach constructs a multi-resolution manifold over SAE feature embeddings and enables progressive navigation from coarse concept clusters to fine-grained neighborhoods, supporting discovery, comparison, and relationship analysis among concepts. We demonstrate the utility of Concept Explorer on SAE features extracted from SmolLM2, where it reveals coherent high-level structure, meaningful subclusters, and distinctive rare concepts that are hard to identify with existing workflows.
format Preprint
id arxiv_https___arxiv_org_abs_2603_23524
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Navigating the Concept Space of Language Models
Marcílio-Jr, Wilson E.
Eler, Danilo M.
Computation and Language
Artificial Intelligence
Sparse autoencoders (SAEs) trained on large language model activations output thousands of features that enable mapping to human-interpretable concepts. The current practice for analyzing these features primarily relies on inspecting top-activating examples, manually browsing individual features, or performing semantic search on interested concepts, which makes exploratory discovery of concepts difficult at scale. In this paper, we present Concept Explorer, a scalable interactive system for post-hoc exploration of SAE features that organizes concept explanations using hierarchical neighborhood embeddings. Our approach constructs a multi-resolution manifold over SAE feature embeddings and enables progressive navigation from coarse concept clusters to fine-grained neighborhoods, supporting discovery, comparison, and relationship analysis among concepts. We demonstrate the utility of Concept Explorer on SAE features extracted from SmolLM2, where it reveals coherent high-level structure, meaningful subclusters, and distinctive rare concepts that are hard to identify with existing workflows.
title Navigating the Concept Space of Language Models
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2603.23524