In Diagrammatic Representation and Inference 14th International Conference, Diagrams 2024, Münster, Germany, September 27 – October 1, 2024, Proceedings. Cham: Springer. pp. 476-479. 2024The Region Connection Calculus (RCC) is a qualitative spatial reasoning formalism, developed in knowledge representation and geographical information systems. We argue that RCC can be viewed as a more fine-grained approach to the use of Euler diagrams to visualize categorical statements like ‘all A are B’. We pr