We consider database schemas consisting of a single binary relation, with key constraints and inclusion dependencies. Over this space of 20 schemas, we completely characterize when one schema is generically dominated by another schema. Generic dominance, a classical notion for measuring information capacity, expresses that every instance of a schema can be uniquely represented in the dominating schema, through application of a deterministic, generic data transformation. Our investigation is motivated both by current interest in schema design for graph databases, as well as by intrinsic scientific interest. We also consider the ternary case, but without inclusion dependencies, and discuss how the notions change in the presence of object identifiers.

翻译：我们考虑由单一二元关系组成的关系数据库模式，并带有键约束与包含依赖。在这20个模式的构成的空间中，我们完全刻画了当一个模式被另一个模式通用支配的条件。通用支配是衡量信息容量的经典概念，它表示通过确定性通用数据变换，某一模式的每个实例都能在支配模式中得到唯一表示。本研究既受当前图数据库模式设计兴趣的驱动，也出于内在的科学兴趣。我们还考虑了不含包含依赖的三元关系情形，并讨论了在对象标识符存在的情况下这些概念的变化。