Hi,

Does anybody have some theoretical idea about functional dependencies.

I have to find non redundant covers and convert a relation to BCNF. But i am unable to understand the concept.

My question is:

Consider the following relations and the set of Function Dependencies(FDs):
SHIPMENT (ship_id, S_capacity, S_date, cargo, amount)
FDs are as follows:
Ship_id -->S_capacity
Ship_id, S_date --> cargo
Cargo, S_capacity --> amount

Now perform the following:
(i) Identify the key of the relation.
(ii) Find the non-redundant cover of the given FDs.
(iii) Normalize the relation into BCNF. Is the decomposition dependency preserving? Give reason for your answer.

Anyone who can help me out??????

homework!!!

no, nobody here can help you

What Rudy means is - we aint doing it for you!
Do the assignment as best as you can and you can ask for critique here.

Sure. This guy has nothing but theoretical ideas about functional dependencies: Associative Model of Data Architecture

Yes... Thanks all....
Finally I found it myself...... though it was difficult to understand from books...
(i) Key for the relation is (ship_id,s_date) because there does not exist any dependency as R-->key for key being a proper subset of R+. and all attributes are dependent on the key.
(ii) None of the given dependencies is redundant. So, non redundant cover for the dependency set is (Ship_id -->S_capacity;Ship_id, S_date --> cargo;Cargo, S_capacity --> amount)
(iii)Converting to the BCNF gives the following three relations for breakup of the given one:
shipment1(Ship_id,S_capacity);
shipment2(ship_id,s_date);
shipment2(ship_id,Cargo,amount)