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.