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Functional Dependencies PPT Notes

Question asked by ISHAN TOPRE in #Coffee Room on Mar 19, 2011
ISHAN TOPRE
ISHAN TOPRE 路 Mar 19, 2011
Rank A2 - PRO
I friends I found these notes when I was studying Normalization.I hope you find them useful. 😀 Posted in: #Coffee Room
ISHAN TOPRE
ISHAN TOPRE 路 Mar 19, 2011
Rank A2 - PRO
Re: Functional Dependencies

Also see this! 馃槢
kevin88
kevin88 路 Mar 19, 2011
Rank E1 - BEGINNER
Hello

I am having a problem understanding dependency theory using Armstrong's Axioms, I have researched this online and I understand the axioms however I am struggling to understand a particular example. Can anyone provide me with any advice or help?

Can I post the example here?

Thank you
ISHAN TOPRE
ISHAN TOPRE 路 Mar 19, 2011
Rank A2 - PRO
Yes of course you can post your query here. Our CS/IT people will try to explain you the theory so that you will be able to solve your problem. 馃榾
kevin88
kevin88 路 Mar 19, 2011
Rank E1 - BEGINNER
Thank you ishutopre

I have two examples with answers but I do not understand how the answer has been derived:

Example 1:
Given
R < A= {V,W,X,Y,Z},
Gamma = { 1. V -> Y, 2. YW -> Z
3. Y -> W}>

RTP(required to prove) VWY -> Z and VXY ->Z

Answers:
VWY -> WY -> Z
VXY -> Y -> YW -> Z
augment 3 by Y Y -> W

Example 2:
Given the following relation
R < A = {M,N,O,P,Q,R,S},
Gamma = {Q->MO, S->R, M->SP}>

prove that PM->R

Answer:
PM -> SP -> S -> R
M -> SP augment by P

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