HALvest-Contrastive: Retrieval-like Authorship Attribution with Patch-level Late Interaction

Francis Kulumba, Wissam Antoun, Guillaume Vimont, Laurent Romary, Florian Cafiero


Abstract
Authorship attribution is the process of identifying the writer of a disputed text by analyzing distinctive stylistic patterns. By comparing the disputed text against a baseline of known authorship, the task amounts to assessing how strongly the two texts are likely to share an author. However, topical confounding makes the task deceptively easy: two authors covering the same topic may look more alike than one author covering two topics. Scholarly prose offers a natural solution. Academic writers produce multiple papers on related but distinct topics while maintaining consistent stylistic habits. Thus, we introduce HALvest-Contrastive, an English benchmark that draws same-author passages from distinct papers within a disciplinary field to reduce topical overlap, while using different-author passages from the same field to discourage naive keyword matching. The benchmark’s design removes topical shortcuts: a strong lexical baseline fails under these constraints. As a by-product of our benchmark construction, we release the 17B-token multilingual corpus used to produce it. We then revisit how to score authorship: while standard systems compress each document into a single vector, we retain the sequence of token-level representations produced by a language model and compare them with late interaction. We also study patch-level late interaction, which groups neighboring tokens into patches before interaction. Matching at the token level increases Recall@20 by a factor of three to five. The optimal interaction granularity, however, depends on sequence length, with no single granularity performing best across all settings.
Anthology ID:
2026.emnlp-main.2660
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
60552–60571
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2660/
DOI:
Bibkey:
Cite (ACL):
Francis Kulumba, Wissam Antoun, Guillaume Vimont, Laurent Romary, and Florian Cafiero. 2026. HALvest-Contrastive: Retrieval-like Authorship Attribution with Patch-level Late Interaction. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 60552–60571, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
HALvest-Contrastive: Retrieval-like Authorship Attribution with Patch-level Late Interaction (Kulumba et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2660.pdf