database - Trouble decomposing to 3rd Normal Form (DB) -

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i've started studying data bases i'm struggling specific part.

i've read definition of each normal form still can't seem understand. here's example couldn't solve properly:

**r(a,b,c,d,e,f)** a->b; b->cd; ad->e

solution: r1(*a*,b,e); r2(*b*,c,d); r3(*a*,*f*)

i can't understand why r3 that

r3 make sure in 2nd normal form , there no update anomaly. f in r1 lead duplicate rows of a,b,e there multiple f values a. b , e values might either ambiguous or redundant.


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