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Let be

F = { AB → C,
       B → D,
      CD → E,
      CE → GH,
       G → A }

some functional dependencies.

Do we have, thanks to Amstrong's axioms or its corollaries AB → G?

My attempt

I don't think so because

AB → C
CE → GH

Then from the pseudo-transitivity rule:

{X → Y, WY → Z}⊨XW → Z

Then

ABE → GH

And tht's all. We can't get rid of H.

1 Answer 1

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This is rather easy.

AB → C
B → D

therefore:

AB → C
AB → D

and:

AB → CD

Next:

AB → CD
CD → E

therefore:

AB → E

with: AB → C
we get:

AB → CE

And finally:

CE → GH

thus:

CE → G

and with the (previous): AB → CE

AB → G

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