Doktorsavhandling

Xixi Liu, Signalbehandling och medicinsk teknik

Towards Reliable Deep Foundation Models in OOD detection, model calibration, and hallucination mitigation

Översikt

Despite the success and potential of deep learning techniques, ensuring the reliable deployment of such models remains a primary concern. In this thesis, the reliability of deep models is tackled through the lens of out-of-distribution (OOD) detection, model calibration, and hallucination mitigation to contributing to a trustworthy artificial intelligence (AI) system. 

Paper A and Paper B utilize joint energy-based modeling (JEM), and develop a probabilistic classifier and regressor, respectively. Specifically, Paper A addresses the training instability of joint energy-based models by replacing stochastic gradient Langevin dynamics with slice score matching, which results in a smoother training procedure without compromising the OOD performance. Paper B extends the idea of JEM from classification to regression, leading to a better calibrated regressor.

Paper C focuses on large-scale OOD detection with standard discriminative classifiers and proposes a novel OOD score based on generalized entropy, utilizing only information from the probability space.

Paper D leverages transfer learning and self-supervised learning techniques to devise an efficient framework, in which only normal samples are required for detecting anomalies in Chest X-rays.

Paper E utilizes the powerful text-image alignment in contrastive vision-language models (VLMs) for zero-shot OOD detection.

Finally, Paper F leverages insights from OOD detection and proposes an energy-based decoding method to mitigate object hallucination in generative VLMs.