A Framework to Categorise Modified General-Purpose AI Models as New Models Based on Behavioural Changes
Pacchiardi, L., Burden, J., Martinez-Plumed, F., Hernandez-Orallo, J., Fernandez Llorca, D., Gomez, E.
Pacchiardi, L. et al. - European Commission, Joint Research Centre (Publications Office of the European Union), 2025-10-10
Abstract
This report discusses an approach for a criteria to determine when a modified General-Purpose AI (GPAI) model should be considered a new and distinct model for regulatory purposes under the EU AI Act. It presents two approaches to assess behavioural changes in altered models: (1) directly measuring differences in capability profiles or instance-level answers, and (2) using proxy metrics related to the alteration process, such as finetuning, computation, and data usage. The report highlights the challenges of establishing thresholds for determining when an altered model is considered a new one and suggests empirical studies to validate the relationships between alteration metrics and downstream behavioural changes.