What is multivalued dependency?

Multivalued dependencies are also referred to as tuple generating dependencies. After the Boyce -Codd normal form the results may be devoid of any functional dependencies but it may encounter multivalued dependencies as the multivalued dependencies also cause redundancy of data.

For eg:

If there are 3 attributes involved in a relation,A,B, and C..

Then for every value of A we will have respective values for B and C.. But it is a necessary in the 4th normal form that both B and C values are independent of each other.

This is represented by .,,

A->>B

A->>C..

MVD or Multivalued Dependency is a dependency where one attribute value is potentially a "multivalued fact" about another and the attributes must be independent of each other.