An Extended Set-Theoretic Relational Model for Multi-Valued Attributes

The classical relational model, as proposed by Codd, is based on a rigid set structure where each attribute takes an atomic value. However, current data modeling needs, especially in semi-structured systems, require the representation of multi-valued attributes. In this paper, we propose a rigorous mathematical model extending the relational model to allow for multivalued attributes, while maintaining set consistency. We define the formal structure of this model, illustrate its operation through examples, and discuss its advantages and possible integration with modern databases.