What Is Meant by the Closure of a Set of Functional Dependencies?

A functional dependency is a one-way dependency between two attributes at any given time. For a unique attribute

of value A there is one value of the attribute B associated with it through the relation. Even if the values for the attribute change, there is only one, as described by Harrington(2009). A functional dependency, as explained by Elmasri & Navathe (2015), is a constraint between two sets of attributes from the database.

Elmasri & Navathe (2015) defined F as a set of functional dependencies that are specified on relation schema R. They go on to describe a closure F+ of F as a set of all functional dependencies that could be inferred from F.

References

Elmasri, R., Navathe, S. B. (2015). Fundamentals of Database Systems, 7th Edition [VitalSource Bookshelf version]. Retrieved from https://bookshelf.vitalsource.com/books/9781323139899

Harrington, J. L. (2009). Relational Database Design and Implementation. : Elsevier Science. Retrieved from http://www.ebrary.com