Re: Basic relational theory help

dontknow105_at_yahoo.com (Bob) wrote in message news:<140cd8ed.0311171447.2aba2b09_at_posting.google.com>...
> My professor and my TA skipped their office hours and Im totally lost.
> Can someone give me a hand? They also rarely respond to emails. Just
> looking for guidance since Im confused.
>
>
> Consider relation schema R(A,B,C) and the set of functional
> dependencies
> F={B->A,A->C}
>
> 1. All non-trivial relations. Is this correct? Im just guessing.
> B->A, A->C,B->C,AB->BC,AC->C, BC->CA,AB->C
>
>
> 2. Find a non-empty instsance of R(give a number of rows) that
> satisfies every Functional Dependency in F.
> Is this correct?
> A B C
> 2 1 3
> 3 2 4
> 4 3 5
>
>
> 3. Find an instance in R that satisfies every FD in F accept A->B
>
> How do you get A->B???? I dont see it.
>
>
>
> 4. Possible to find an instance an instance that satisfies every FD in
> F, but does not satisfy the FD AB->C. I have no idea. Im totally lost.
>
> Can someone point in the right direction?

please? I read my textbook, plus the silbershatz book. Professor didnt cover all this in class and blew off his office hours. Im just looking for a helping hand. I searched the web, but its just a rehash of whats in the book. I am NOT mathematically inclined. Received on Tue Nov 18 2003 - 16:23:54 CET