ERC Starting Grant: Michael Hahn to tackle fundamental flaws in large language models
Computational linguist Michael Hahn has now been awarded a European Research Council (ERC) Starting Grant worth €1.5 million over five years. Photo: © Thorsten Mohr/UdS
Large language models such as ChatGPT have become an integral part of everyday life for many people and businesses. They are being used, e.g., to gather information from multiple sources and to support complex planning processes. Yet these AI systems are not infallible and they continue to make mistakes – LLMs hallucinate and struggle to combine information in a logically rigorous manner. Computational linguist Michael Hahn has set out to strengthen the theoretical foundations of AI reasoning.
He has now been awarded a European Research Council (ERC) Starting Grant worth €1.5 million over five years to pursue this work.
Large language models are being used to handle increasingly complex tasks to which they are not yet particularly well suited. Problems arise when companies use these models to manage complex planning scenarios such as coordinating staff rotas with material deliveries, production processes and delivery deadlines. ‘Language models still struggle with sequences of interdependent events, especially when the relevant information comes from different sources. When drawing up a staffing rota, for example, a model must take account of when materials will arrive, which production steps depend on them and whether enough staff are available to meet the delivery deadline. We want to understand how the theoretical foundations of language models need to be improved so that they can keep track of such interdependent sequences more reliably,’ says Michael Hahn, Professor of Computational Linguistics at Saarland University. Using large datasets, he and his team want to investigate which relationships AI systems can infer successfully from the data and identify those cases where they still fall short.
‘Large language models find it particularly difficult to distinguish between very similar pieces of information. This is the case, for example, in biomedical research, where descriptions of molecules and cellular processes may differ only in subtle respects,’ explains Michael Hahn. Hahn wants to develop a deeper scientific understanding of how AI systems learn and how they arrive at conclusions step by step. ‘Inductive bias plays a key role,’ says Hahn. ‘This is the set of assumptions and prior knowledge that a machine-learning algorithm needs in order to be able to generalize from familiar training data to data it has not encountered before.’
He and his team will examine the underlying mathematical models in depth and plan to develop a theory to explain how different training conditions affect the ability of an AI system to develop the low-level and high-level reasoning required to reach a well-founded conclusion. ‘We want to develop the theory using real-world tasks so that we can both predict and prevent model errors. Our goal is to make language models more reliable and cost-effective and, ultimately, help pave the way for trustworthy AI,’ says Hahn.
Michael Hahn has now been awarded an ERC Starting Grant worth €1.5 million over five years for his project ‘REALM: Foundations for Reliable Language Model Reasoning via Inductive Biases’. Last year, he received a similar amount through the German Research Foundation’s Emmy Noether Programme to gain a better understanding of the fundamental architecture of language models and explore new approaches to their design (see press release of 19 November 2025). In March, Michael Hahn was also awarded the Heinz Maier-Leibnitz Prize.
Computational linguist Michael Hahn is a member of Saarland University’s Department of Language Science and Technology, which conducts internationally renowned research and teaching at the intersection of language, cognition and artificial intelligence. The department maintains close links with the Saarland Informatics Campus. In the latest funding round, Yiting Xia and Thomas Leimkühler of the Max Planck Institute for Informatics also received ERC Starting Grants. This brings the number of researchers at the Saarland Informatics Campus who have secured one of the European Union’s various ERC grants to 54. Of the 421 ERC Starting Grants awarded in the current round, 22 are in the field of computer science. Only five of these went to Germany, three of them to the researchers at the Saarland Informatics Campus named above.
Background information – Saarland Informatics Campus
One thousand scientists and about 2,800 students from more than 81 nations make the Saarland Informatics Campus (SIC) one of the leading locations for computer science in Germany and Europe. Four world-renowned research institutes, namely the German Research Center for Artificial Intelligence (DFKI), the Max Planck Institute for Informatics, the Max Planck Institute for Software Systems, the Center for Bioinformatics as well as Saarland University with three departments and 24 degree programs cover the entire spectrum of computer science. https://saarland-informatics-campus.de/
Further information:
ERC Starting Grants 2026: https://erc.europa.eu/news-events/news/erc-2026-starting-grants-results
Department of Language Science and Technology at Saarland University
Professor Michael Hahn’s personal website: https://www.mhahn.info
Questions can be addressed to:
Professor Michael Hahn
Language, Computation and Cognition Lab
Tel. +49 681 302-4343
Email: mhahn(at)lst.uni-saarland.de