pzozulka
asked on
Canonical Cover
I need help finding canonical cover for the following dependencies:
AB->CD
BCD->EF
BC->D
EB->A
D->B
This is for a practice assignment, however, the only thing we've learned so far are the armstrong axioms, and it doesn't seem like I can apply those here. The book talks about eliminating extraneous attributes, however the algorithms they use in the book is complicated and I don' understand it. Hoping someone here is able to provide a solution, and an english version interpretation of how to solve future canonical covers.
Thank you.
AB->CD
BCD->EF
BC->D
EB->A
D->B
This is for a practice assignment, however, the only thing we've learned so far are the armstrong axioms, and it doesn't seem like I can apply those here. The book talks about eliminating extraneous attributes, however the algorithms they use in the book is complicated and I don' understand it. Hoping someone here is able to provide a solution, and an english version interpretation of how to solve future canonical covers.
Thank you.
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Well, I suppose I should understand it all, as I've been using relational databases since about 1987, but they weren't on the curriculum when I took Comp Sci :( In fact, they didn't exist! I'll be honest - I happened to know those refs, but that's all, unless I take the course too!
Good luck
Mike
Good luck
Mike
The minimal cover for the problem is
AB->C
BCD->E
BCD->F
BC->D
EB->A
D->B
AB->C
BCD->E
BCD->F
BC->D
EB->A
D->B
ASKER
The first link you sent is exactly the part of the textbook that I needed help interpreting into regular english. It just doesn't make any sense to me. I just don't seem to understand how to check for extraneous attributes. For example in the example I posted above, BCD->EF, how do you check if B is extraneous in the left hand side. And how do you check if D is extraneous on the left hand side?
The second link is what I've used over and over to double check my work, and so far I guess I'm not doing it right.