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From: "Mike M" <mike.m.news@googlemail.com>
Newsgroups: comp.databases.theory
Subject: Find Candiate Keys - is there a short cut?
Date: 3 Mar 2007 08:19:32 -0800
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Hi,

I'm wondering if there is any tip or trick how to find ALL candidate
keys (CK) for a relation and its FDs, w/o using kind of "brute force"
mechanism and trying whether a certain attribute (or composites of
attributes) is CK?

Eg, if there is a relation R=ABCDEFG with following dependencies:
F={AB-->CD, DE-->AB, AC-->F, BF-->EG, E-->C, G-->H, H-->BF}

I found {A,B}, {A,G}, [A,H}, {D,E}, {D,G}, {D,H}, and {B,D,F} as CKs.
I used brute force taktic to get them, but it took me quite a while -
and if I don't want to go through all possibilities of composed
attributes of R, I'm not even sure whether this list is exhaustive (to
my knowledge...).

Sure, finding eg CK {A,B} eliminates other possibilities containing A
and B. Still, it just seems not to be the best way. Is there any
other?

Thanks for help!
Mike