Our paper “The Trigger Is in the Embedding: Supervision-Free Discovery and Diagnosis of Universal Adversarial Triggers in Fact Verification”, by Michele Luca Contalbo, Matteo Paganelli, Paolo Papotti, and Francesco Guerra, has been accepted as a Main Conference paper at EMNLP 2026, taking place in Budapest, Hungary, from October 24–29, 2026.
The paper introduces FactFlip, a supervision-free approach for discovering universal adversarial triggers in fact verification models. These triggers are words that, when inserted into otherwise unchanged claims, can systematically bias model predictions toward a target class.
Unlike existing gradient-based approaches, FactFlip requires no labeled data and no gradient optimization. It identifies candidate triggers directly from the model’s embedding space by measuring their alignment with the classification weights.
Experiments across six datasets and different encoder- and decoder-based models show that FactFlip can identify effective and compositional triggers while achieving results close to gradient-based methods. The approach also provides a diagnostic tool for investigating systematic model biases.
The code is publicly available on GitHub.



