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Homework Help: Difficulties with getting a relation into 3NF

  1. Feb 24, 2016 #1
    1. The problem statement, all variables and given/known data

    Decompose R into dependency preserving 3NF

    2. Relevant equations
    F = {D->F, AB->C, E->F, C->BD, D->E}

    3. The attempt at a solution
    My attempt is to first construct the minimal basis for the FD set F, which is G={A->C, E->F, C->B, C->D, D->E} (hopefully correct). Then I created a set of relations over all the FD's in G, which is as following:


    Then I also add a relation, whose schema forms a key. The key for the relation R is AB and therefore I added S5(AB), so the complete solution is:


    But afterwards, when I test this solution if it fills the requirements to be in 3NF, then it is incorrect. Firstly, my definition of a relation in 3NF is if X->A is a FD that holds in a relation, then X is a superkey or A is a prime (an attribute that is part of a key). The functional dependency C-D will fail in my solution because it doesn't fill either of the requirements.

    Have I constructed the minimal basis incorrectly? I don't know why I can't get this all right.

    If you have a very simple and effective algorithm to decompose a relation into 3NF, then please let me know it so I will be better at decomposing relations into 3NF.

    Thanks for your help!
  2. jcsd
  3. Feb 29, 2016 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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