International audienceIn model-driven engineering, correct model transformation is essential for reliably producing the artifacts that drive software development. While the correctness of a model transformation can be specified and checked via contracts, debugging unverified contracts imposes a heavy cognitive load on transformation developers. To improve this situation, we present an automatic fault localization approach, based on natural deduction, for the ATL model transformation language. We start by designing sound natural deduction rules for the ATL language. Then, we propose an automated proof strategy that applies the designed deduction rules on the postconditions of the model transformation to generate sub-goals: successfully provi...