Say No More! Exploring Linguistic Negation in (M)LLMs for AI Safety

Abstract: Large Language Models (LLMs) and their multimodal counterparts (MLLMs) have shown outstanding performance across a wide range of tasks. However, they often remain surprisingly incapable of handling assignments that are straightforward for humans. One of these is linguistic negation. Previous work on the topic is still scarce, but there is already evidence showing that the negation problem is pervasive in both pure NLP tasks, such as semantic textual similarity or text-to-text retrieval, as well as multimodal settings like text-to-image generation, image segmentation, visual question answering, or cross-modal retrieval. In my work, I will focus on two different avenues related to this linguistic construct. On the one hand, it appears that negation is an easy and effective method to jailbreak (M)LLMs, getting them to output harmful or unethical content with implications in AI Safety and Security. On the other hand, there is still great room for improvement in negation understanding in the aforementioned multimodal tasks. As an amusing example, models have a hard time generating an image of a "room without an elephant" or "a tennis ball with no white lines."

Short bio: Diego Miguel Lozano is a PhD student at ELLIS Alicante. He holds a Bachelor's Degree in Computer Science from the University of Burgos, with a thesis focused on Abstractive Summarization, and a Master’s Degree in Computer Science from the Technical University of Munich (TUM) with a focus on NLP and, more concretely, Semantic Textual Similarity. He has also several years of industry experience in Information Retrieval and Question Answering. Diego’s current PhD is framed within the field of AI Security, with a focus on multimodal LLMs. His supervisors are Dr. Nuria Oliver (ELLIS Alicante), Dr. Erik Derner (Czech Technical University), and Dr. Juan Antonio Pérez Ortiz (University of Alicante).

Presenter: Diego Miguel Lozano

Date: 2026-01-30 11:00 (CET)

Location: Oficinas ELLIS Alicante, Muelle Pte., 5 – Edificio A, Alicante 03001, Alicante ES

Online: https://teams.microsoft.com/meet/34908044548616?p=7q4QQqPnAcFrapBpYg

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