Model-versioning-in-the-large: algebraic foundations and the tile notation

Model-versioning-in-the-large is concerned with complex scenarios involving multiple updates and multiple replicas of a model. The paper introduces tile systems as rephrasing of double categories in model versioning terms, and shows that the tile language enables a very general formalization of versioning concepts. The formalization makes the concepts amenable to algebraic analysis and provides a convenient notation for version system designers. It also allows one to formulate algebraic laws that a correct versioning system must or may want to satisfy.