SubmissionNumber#=%=#162 FinalPaperTitle#=%=#DUTh at SemEval-2024 Task 6: Comparing Pre-trained Models on Sentence Similarity Evaluation for Detecting of Hallucinations and Related Observable Overgeneration Mistakes ShortPaperTitle#=%=# NumberOfPages#=%=#7 CopyrightSigned#=%=#Ioannis Maslaris JobTitle#==# Organization#==#Database & Information Retrieval research unit, Department of Electrical & Computer Engineering, Democritus University of Thrace, Greece Abstract#==#In this paper, we present our approach to SemEval-2024 Task 6: SHROOM, a Sharedtask on Hallucinations and Related Observable Overgeneration Mistakes, which aims to determine weather AI generated text is semantically correct or incorrect. This work is a comparative study of Large Language Models (LLMs) in the context of the task, shedding light on their effectiveness and nuances. We present a system that leverages pre-trained LLMs, such as LaBSE, T5, and DistilUSE, for binary classification of given sentences into ‘Hallucination' or ‘Not Hallucination' classes by evaluating the model's output against the reference correct text. Moreover, beyond utilizing labeled datasets, our methodology integrates synthetic label creation in unlabeled datasets, followed by the prediction of test labels. Author{1}{Firstname}#=%=#Ioanna Author{1}{Lastname}#=%=#Iordanidou Author{1}{Username}#=%=#ioannaior Author{1}{Email}#=%=#ioaniord1@ee.duth.gr Author{1}{Affiliation}#=%=#Democritus University of Thrace Author{2}{Firstname}#=%=#Ioannis Author{2}{Lastname}#=%=#Maslaris Author{2}{Username}#=%=#yms1 Author{2}{Email}#=%=#yannismslr@gmail.com Author{2}{Affiliation}#=%=#Democritus University of Thrace Author{3}{Firstname}#=%=#Avi Author{3}{Lastname}#=%=#Arampatzis Author{3}{Username}#=%=#avi1 Author{3}{Email}#=%=#yannis.maslatis@gmail.com Author{3}{Affiliation}#=%=#Democritus University of Thrace ========== èéáğö