Object-Role Modeling (ORM) is a conceptual modelling language used to represent information about the object types, relationships, and constraints of a particular domain. Finite model theory is a subfield of mathematical logic that studies the properties and limitations of models that have a finite size.

Dr. Terry Halpin's PhD thesis proposes a mapping of Object-Role Modeling diagrams to a first-order theory under finite-model theory called KL (Knowledge Language).

In the thesis, Halpin shows how ORM can be mapped to KL by defining a mapping from ORM constructs to KL constructs. This mapping allows ORM models to be translated into a KL theory, which can then be analysed using the tools and techniques of finite-model theory.

The KL theory defined by Halpin consists of a set of effective axioms that describe the concepts, relationships, and constraints in the graphical ORM modelling language. The then mapping of ORM diagrams (sentences of ORM) to sentences of KL can be used to reason about the properties of the ORM model.

The mapping of ORM to KL enables the application of logical tools to ORM models, which can help to reveal the properties and limitations of the model and aid in the development of more accurate and efficient conceptual models.