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The concept of MVD or Multivalued dependency refers to having multiple rows in a given table. Thus, it implies that there is a presence of multiple other rows in the very same table. Thus, a multivalued dependency would prevent the 4NF. Any multivalued dependency would at least involve three attributes of any table.

Fourth normal form (4NF) is a level of database normalization where there are no non-trivial multivalued dependencies other than a candidate key. It builds on the first three normal forms (1NF, 2NF and 3NF) and the Boyce-Codd Normal Form (BCNF).

The criteria to normalize to 4NF is that it need to meet BCNF and multiple value of B exists for a single value of A given A->B.

4NF in DBMS stands for Fourth Normal Form and the relation is said to be in 4NF if the relation is in Boyce Codd Normal Form and has no multi-valued dependency. Multi-valued dependency for a relation A −> B exists when for a single value of A, multiple values of B exist.

A relation is said to be in 4NF if the relation is in Boyce Codd Normal Form (BCNF) and has no multi-valued dependency. Multi-valued dependency for a relation A −> B exists when for a single value of A, multiple values of B exist, also the table should have at least 3 columns.

However, in a theoretical sense, the anomalies are caused by the presence of a multivalued dependency in the same relation, which must be eliminated to get to fourth normal form. The rules for fourth normal form are: The relation is in BCNF. There are no multivalued dependencies.

An attribute may multidetermine another (X→→Y). For example, a student (identified by Student_ID) may take many courses (identified by Course). Thus Student_ID→→Course. This is called a multivalued dependency. A table violates fourth normal form when it contains two or more independent multivalued dependencies.