Information Modeling and Relational Databases, 2nd Edition

6.7. Summary

A set is determined by its members, so order and repetition don’t matter, e.g., {3, 6} = {6, 3, 6}. A bag or multiset makes repetition significant, e.g., [3, 6] = [6, 3] but [3, 6] ≠ [3, 6, 6]. A sequence is an ordered bag, e.g., (3, 6) ≠ (6, 3). A set A is a subset of B (written A ⊆ B) iff each member of A belongs to B; in this case B is a superset of A. A is a proper subset of B iff A ⊆ B and A ≠ B. A and B are mutually exclusive or disjoint iff they have no common members, i.e., their intersection, A ∩ B = { }. If sets have common members they overlap; if each also has extra members, we have a case of proper overlap.

CSDP step 6 adds any value, set-comparison (subset, equality, exclusion), and subtype constraints. A value constraint ...