A Basic Characterization of Relation Migration
Representing and reasoning over evolving objects has been investigated widely. Less attention has been devoted to the similar notion of relation migration, i.e., how tuples of a relation (ORM facts) can evolve along time. We identify different ways how a relation can change over time and give a logic-based semantics to the notion of relation migration to capture its behaviour. We also introduce the notion of lifespan of a relation and clarify the interactions between object migration and relation migration. Its use in graphical conceptual data modelling is illustrated with a minor extension to ORM2 so as to more easily communicate such constraints with domain experts.