A set of FDs for the relation R{A, B, C, D, E, F} is AB →C, C → A, BC → D,ACD → B, BE → C, EC → FA, CF → BD, D→ E. Find a minimum cover forth is set of FDs.
Question
A set of FDs for the relation R{A, B, C, D, E, F} is:
- AB → C
- C → A
- BC → D
- ACD → B
- BE → C
- EC → FA
- CF → BD
- D → E
Find a minimum cover for this set of FDs.
Solution
To find a minimum cover for the set of functional dependencies (FDs), we need to follow three steps:
-
Left Reduction: In this step, we try to remove extraneous attributes from the left-hand side (LHS) of each FD. An attribute is extraneous if removing it does not change the closure of the set of FDs.
-
Right Reduction: In this step, we try to remove extraneous attributes from the right-hand side (RHS) of each FD. An attribute is extraneous if removing it does not change the closure of the set of FDs.
-
Union Rule: In this step, we combine FDs that have the same LHS.
Let's apply these steps to your set of FDs:
-
Left Reduction:
- AB →C, C → A, BC → D,ACD → B, BE → C, EC → FA, CF → BD, D→ E
- After left reduction, we get: B →C, C → A, BC → D, CD → B, BE → C, EC → FA, CF → BD, D→ E
-
Right Reduction:
- B →C, C → A, BC → D, CD → B, BE → C, EC → FA, CF → BD, D→ E
- After right reduction, we get: B →C, C → A, BC → D, CD → B, BE → C, EC → F, CF → B, D→ E
-
Union Rule:
- B →C, C → A, BC → D, CD → B, BE → C, EC → F, CF → B, D→ E
- After applying the union rule, we get: B →C, C → A, BC → D, CD → B, BE → C, EC → F, CF → B, D→ E
So, the minimum cover for the given set of FDs is: B →C, C → A, BC → D, CD → B, BE → C, EC → F, CF → B, D→ E.
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