Social media is a key channel for information dissemination, making effective rumor detection essential to mitigate misinformation’s societal impact. Although large language models excel in inference and text generation, they struggle with understanding propagation relationships and complex reasoning tasks like rumor detection. Existing methods mainly rely on textual information and event propagation structures, but provocative comments and unreliable interactions increase propagation uncertainty. To address these challenges, we propose an Emotionally-Aware Structural Enhancement Graph Auto-Encoder (EASE-GARD) to improve rumor representations. Our method begins by enhancing the textual representation of responses through the generation of emotive adversarial comments. It then generates and differentiates false local propagation relationships (fabricated forwards and reciprocations) to reduce propagation uncertainties. A graph auto-encoder captures contextual features and global structural information and recalculates forwarding probabilities among responses. Extensive experiments show our model performs best on all three datasets, excelling in effectiveness and robustness.

The rapid rise of social networks has led to a proliferation of fake news, especially those with images. The combination of images and text may confuse users and cause even more negative impact. Exisiting methods for fake news detection either require expert knowledge or large amounts of labeled data. In addition, these methods fails to clarify which part of the multimodal information is misleading or why. In this paper, we present a simple yet efficient Chain-of-thought Prompting method for Multimodal Fake News Detection (CP-FEND). It first finds the closest demonstration samples of the news posts to be detected by a KNN-based approach. Afterwards, we design a logical prompt method including Examination, Inference and Determination stages to guide Large Language Model (LLM) to automatically construct reasoning processes for the authenticity of the samples. Finally, LLM are prompted to derive the authenticity of multimodal news with the guidance of samples and Chain-of-Thought reasoning. A reflective verification is performed to further improve the detection performance through comprehensive evaluation of the original responses. Extentsive experiments on two public datasets have demonstrated the superiority of our method over existing methods.

Existing studies for rumor detection rely heavily on a large number of labeled data to operate in a fully-supervised manner. However, manual data annotation in realistic cases is very expensive and time-consuming. In this paper, we propose a novel self-supervised Relation-Event based Contrastive Learning (RECL) framework for rumor detection to address the above issue. Specifically, we present both the relation-level and event-level augmentation strategies to generate contrastive samples, which capture both the semantics revealed by repost relations and the structural features of rumor events. Moreover, contrastive learning tasks are devised to generate informative graph representations by utilizing self-supervision signals of unlabeled data. Extensive experimental results on real-world datasets demonstrate the effectiveness of our model, especially with limited labeled data.

Online reviews play a significant role in purchase decisions of consumers by providing feedback information from buyers of products. In order to mislead consumers, opinion spammers are hired to write fake reviews to promote or demote specific products for illegitimate benefits. Existing methods for spam review detection mainly focused on designing manual features, which highly rely on expert knowledge. Although recent works utilized deep learning methods to automatically learn the semantics of reviews through the inherent user-review-product strong relation, they fail to capture the weak relations between reviews at the content, sentiment and temporal levels, which provides various semantic information to expose fake reviews. Moreover, the imbalanced class distribution in spam detection issues makes this work even more challenging. To address the above problems, we propose a novel Weak-Strong Unified Network (WSUN) for opinion spam detection. Multi-level weak relation graphs are constructed to reveal the abnormal behavioral patterns of spammers, which aggregates the semantics of strong relations by graph convolutional networks and extracts comprehensive review representation by utilizing relation-level attention mechanism. In addition, a graph-based over-sampling method is devised to mitigate the impact of imbalanced class distribution. Extensive experimental results on real-world datasets show that our model is more effective than the state-of-the-art methods.