CobwebTM: Probabilistic Concept Formation for Lifelong and Hierarchical Topic Modeling

Karthik Singaravadivelan, Anant Gupta, Zekun Wang, Christopher J. MacLellan


Abstract
Topic modeling seeks to uncover latent semantic structure in text corpora with minimal supervision. Neural approaches achieve strong performance but require extensive tuning and struggle with lifelong learning due to catastrophic forgetting and fixed capacity, while classical probabilistic models lack flexibility and adaptability to streaming data. We introduce CobwebTM, a low-parameter lifelong hierarchical topic model based on incremental probabilistic concept formation. By adapting the Cobweb algorithm to continuous document embeddings, CobwebTM constructs semantic hierarchies online, enabling unsupervised topic discovery, dynamic topic creation, and hierarchical organization without predefining the number of topics. Across diverse datasets, CobwebTM achieves strong topic coherence, stable topics over time, and high-quality hierarchies, demonstrating that incremental symbolic concept formation combined with pretrained representations is an efficient approach to topic modeling.
Anthology ID:
2026.findings-acl.1753
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
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Publisher:
Association for Computational Linguistics
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Pages:
35140–35155
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URL:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.1753/
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Cite (ACL):
Karthik Singaravadivelan, Anant Gupta, Zekun Wang, and Christopher J. MacLellan. 2026. CobwebTM: Probabilistic Concept Formation for Lifelong and Hierarchical Topic Modeling. In Findings of the Association for Computational Linguistics: ACL 2026, pages 35140–35155, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
CobwebTM: Probabilistic Concept Formation for Lifelong and Hierarchical Topic Modeling (Singaravadivelan et al., Findings 2026)
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