A normal form for nested relations
Zehra Meral Ozsoyoglu, Li-Yan Yuan · 1985
We consider nested relations whose schemes are structured as trees, called scheme trees, and introduce a normal form for such relations, called nested normal form.Given a universal scheme U, and a set of multivalued dependencies (MVD's) M, we present an algo rithm to obtain a nested normal form decomposition of U w.r.t.M. Such a decomposition has several desirable properties, such as explicitly representing a set of full and embedded MVD's implied by M, and being a faithful and nonredundant representation of U.Moreover, if M is conflict free, then the nested normal form decomposition is also dependency preserving.Finally, we show that if M is conflict free, then the unique 4NF decomposition [Fa, L2 ] (which is also in SFNF [BK2]), of U is precisely the set of root-to-leaf paths of scheme trees in nested normal form decomposition of U w.r.t.M.