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I have this relation:
R(A,B,C,D,E,G)
F = { AB -> C
AC -> D
AD -> E
B -> D
BC -> A
E -> G }
I need to project the original relation's functional dependencies onto the decomposed relations below. My question is, can I say that R3 carries E->G even though E->G is a deducted functional dependency based on a rule carried by R2? (AD->E)
And if so, is it correct to say that the key for R3 is A, D?
Or that.... no original FDs can pe projected onto R3 (since AD->E is not in THIS relation) and the key is ADG?
R1 (A, B, C) --- AB ->C, BC -> A
R2 (A, C, D, E) --- AC ->D, AD ->E
R3 (A, D, G) – AD->E (given) so E->G (transitive rule)
R(A,B,C,D,E,G)
F = { AB -> C
AC -> D
AD -> E
B -> D
BC -> A
E -> G }
I need to project the original relation's functional dependencies onto the decomposed relations below. My question is, can I say that R3 carries E->G even though E->G is a deducted functional dependency based on a rule carried by R2? (AD->E)
And if so, is it correct to say that the key for R3 is A, D?
Or that.... no original FDs can pe projected onto R3 (since AD->E is not in THIS relation) and the key is ADG?
R1 (A, B, C) --- AB ->C, BC -> A
R2 (A, C, D, E) --- AC ->D, AD ->E
R3 (A, D, G) – AD->E (given) so E->G (transitive rule)
Last edited by Ratte : Nov 13th, 2007 at 1:00 pm.
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