Musings on the Relational Model

The Relational Model is of central importance to data management.

Relaxing constraints on the base relvars serves two purposes. It allows for concurrent data entry of relations using Operational Transformation - mainly because it promotes independently updatable variables, and it addresses the view update problem which is considered in the context of alternative representations (possreps) of the information recorded in the database.

Maximising orthogonality of information suggests the idea of nested relational databases.

Every non-empty relation has a unique prime Cartesian factorisation.

2011-09-15 Nested Data Models.docx is concerned with the question of a maximal partition of the information in a database into orthogonal parts. This means having as many variables as possible which can be updated independently (with an emphasis on relvars and encompassing both base and derived relvars).

2013-02-21 Type Systems.doc concerns a formalism of some the ideas of Chris Date and Hugh Darwen expressed in The Third Manifesto, particularly their Inheritance Model which could be described as subtype as subset and where the types form a lattice.

2013-11-15 Proposal for type system.doc is another formalism of type systems.

Links

• Interfacing CEDA to a conventional RDBMS
• Imperative programming language variables
• type constraint
• conditionally existent L-values
• Information equivalence classes
• Unrolling a predicate
• Factorisation of supplier and parts database schema