In this tutorial, we present a novel ontological theory of relationships and explore its consequences in addressing a number of important and recurrent conceptual modeling problems. These problems range from identity and modality of relationships, taxonomic structures over relations and systematic ambiguity in cardinality constraints.
1. Relations and relationships
2. The needs for reification
2.1 The relation attribute problem
2.2 The cardinality problem
2.3 The problem of anadic relations
3. The nature of reified relationships: Identity and Modality
3.1 Relationships as tuples
3.2 Relationships a facts
3.3 Relationships as episodes (perdurants)
3.4 Relationships as objects (endurants)
4. Ontological patterns involving Relations
4.1 Ontological Meta-Properties and Taxonomic Structures over Relations
4.2 Relation Specialization, Subsetting and Redefinition with an ontological twist
4.3 Ontological Anti-Patterns involving Relations and Reified Relationships
5. Concrete Examples (including a Commitment-Based Service Ontology)
6. Summary of various positions in the literature
