Fagin: multivalued dependencies and lossless fourth-normal-form decomposition

What changed

Fagin connected multivalued dependencies to lossless projection joins, defined fourth normal form beyond Boyce–Codd normal form, and proved finite-schema decomposition can reach it without information loss.

Scientific scope

Fagin connected multivalued dependencies to lossless projection joins, defined fourth normal form beyond Boyce–Codd normal form, and proved finite-schema decomposition can reach it without information loss. The result concerns finite set-valued relations, schema constraints and multivalued dependencies in a specified attribute context. Fourth normal form is stronger than BCNF for this redundancy. Lossless decomposition need not preserve every constraint locally or optimize queries. A property observed in one finite relation does not establish an integrity constraint for all future data. Independent related work retains credit.

Evidence

Source-linked, scoped account of the original work. The published scope states the scientific assumptions and remaining verification limits. WRS has not independently certified the full proof, experimental result or system benchmark.

Contributors

• Ronald Fagin · SCIENCE: Original source-listed scientific author of this scoped work; byline does not determine effort fractions.

• Fagin: multivalued dependencies and lossless fourth-normal-form decomposition — exact original scientific paper
• Fagin: multivalued dependencies and lossless fourth-normal-form decomposition — publisher deposit

Provisional WRS assessment, edition 2026-10-16.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.

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