Bruzzone, ElisabettaDe Floriani, Leila2015-10-052015-10-0519911017-4656https://doi.org/10.2312/egtp.19911008Modular boundary models are a class of solid models which describe a solid object as a collection of face-abutting object parts, called components. The Face-to-Face Composition (FFC) model is a specific model of this class, which encodes both the connection and the interference information among object components. Necessary and sufficient conditions for an FFC model to be valid are defined in terms of a representation of the FFC model, called the FFC graph. The problem of producing valid FFC models from the decomposition of the FFC model of a given object into subobjects is studied in connection with the generation of a production graph.10.2312/egtp.19911008