DeltaSHAP: a Shapley Value Framework for Interpreting Political Ambiguity

Sven-Alexander Gal, Rodica-Ioana Lung


Abstract
Political ambiguity and response clarity have become increasingly important research topics in computational social science and natural language processing. In this paper, we present a solution to the SemEval 2026 Task 6 "Clarity" Challenge. We propose a novel framework that employs TF–IDF representations and Shapley-value–based feature selection for multi-class classification. Shapley-based feature importances are used both for post-hoc explanation and as an active mechanism for label-specific vocabulary selection. For each label, features exceeding a predefined threshold are retained, label-specific vocabularies are filtered through set differences, and independent one-versus-all classifiers are trained using specific features. Experimental results show that threshold tuning substantially impacts performance, with the best performance achieved at intermediate threshold values. Our findings demonstrate that using the game-theoretic feature selection provides an interpretable approach to clarity classification, offering a flexible methodology for ambiguity-sensitive text analysis.
Anthology ID:
2026.semeval-1.368
Volume:
Proceedings of the 20th International Workshop on Semantic Evaluation (2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Ekaterina Kochmar, Debanjan Ghosh, Kai North, Mamoru Komachi
Venues:
SemEval | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2939–2945
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.368/
DOI:
Bibkey:
Cite (ACL):
Sven-Alexander Gal and Rodica-Ioana Lung. 2026. DeltaSHAP: a Shapley Value Framework for Interpreting Political Ambiguity. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 2939–2945, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
DeltaSHAP: a Shapley Value Framework for Interpreting Political Ambiguity (Gal & Lung, SemEval 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.368.pdf