David Heckerman, Christopher Meek, and Daphne Koller
In this chapter, we introduce a graphical language for relational data called the probabilistic entity-relationship (PER) model. The model is an extension of the entity-relationship model, a common model for the abstract representation of database structure. We concentrate on the directed version of the model — the directed acyclic probabilistic entity-relationship model (DAPER) model. The DAPER model is closely related to the plate model and the PRM, existing models of relational data. The DAPER model is more expressive then either existing model. Many examples are provided.