retagged by
7,126 views
18 votes
18 votes

Suppose the following functional dependencies hold on a relation $U$ with attributes $P,Q,R,S$, and $T$:

  • $P \rightarrow QR$
  • $RS \rightarrow T$

Which of the following functional dependencies can be inferred from the above functional dependencies?

  1. $PS \rightarrow T$
  2. $R \rightarrow T$
  3. $P \rightarrow R$
  4. $PS \rightarrow Q$
retagged by

3 Answers

Best answer
21 votes
21 votes
Option A: $(PS)^+ = {P, Q, R, S, T}.$ So, $PS\rightarrow T$ holds.

Option B: $(R)^+ = {R}.$ So, $R\rightarrow T$ does not hold.

Option C: $(P)^+ = {P, Q, R}.$ So, $P\rightarrow R$ holds.

Option D: $(PS)^+ = {P, Q, R, S, T}.$ So, $PS\rightarrow Q$ holds.
edited by
1 votes
1 votes

Check for the reachability using the Closer operation...

Answer:

Related questions