An Algebraic View on the Semantics of model Composition
  Due to the increased complexity of software development projects more and more systems are described by models. The sheer size makes it impractical to describe these systems by a single model. Instead many models are developed that provide several complementary views on the system to be developed. This however leads to a need for compositional models. This paper describes a foundational theory of model composition in form of an algebra to explicitly clarify different variants and uses of composition, their interplay with the semantics of the involved models and their composition operators. 
Christoph Herrmann, Holger Krahn, Bernhard Rumpe, Martin Schindler,   Steven V\"olkel
cs.SE