What is the concept of canonical cover?
A canonical cover is a simplified and reduced version of the given set of functional dependencies. Since it is a reduced version, it is also called as Irreducible set.
Is minimal cover same as canonical cover?
A canonical cover is “allowed” to have more than one attribute on the right hand side. A minimal cover cannot. As an example, the canonical cover may be “A -> BC” where the minimal cover would be “A -> B, A -> C”. That is the only difference.
How is canonical cover calculated?
Steps to find canonical cover:
- There are two functional dependencies with the same set of attributes on the left:
- There is an extraneous attribute in AB C because even after removing AB C from the set F, we get the same closures.
- C is an extraneous attribute in A BC, also A B is logically implied by A B and B.
What is the concept of canonical cover how do you compute it give example?
FD = { B → A, AD → C, C → BD } is Canonical Cover of FD = { B → A, AD → BC, C → ABD }. Example 2: Given a relational Schema R( W, X, Y, Z) and set of Function Dependency FD = { W → X, Y → X, Z → WXY, WY → Z }.
Does a set of FD’s have a unique canonical cover?
No, it cannot be a canonical cover for your set of functional dependencies (FD). A canonical cover of F is a “minimal” set of functional dependencies equivalent to F, having no redundant dependencies or redundant parts of dependencies.
Why is canonical cover not unique?
No, it cannot be a canonical cover for your set of functional dependencies (FD). A canonical cover of F is a “minimal” set of functional dependencies equivalent to F, having no redundant dependencies or redundant parts of dependencies. The canonical cover you suggest is not equivalent to F .
What is difference between canonical form and standard form?
The main difference between canonical and standard form is that canonical form is a way of representing Boolean outputs of digital circuits using Boolean Algebra while standard form is a simplified version of canonical form that represents Boolean outputs of digital circuits using Boolean Algebra.
Is canonical and standard form same?
What is difference between standard form and canonical form?
In standard form Boolean function will contain all the variables in either true form or complemented form while in canonical number of variables depends on the output of SOP or POS. maxterm for each combination of the variables that produces a 0 in the function and then taking the AND of all those terms.
When do you need to use the canonical cover?
If there is a violation of dependencies in the new database state, the system must roll back. Working with a huge set of functional dependencies can cause unnecessary added computational time. This is where the canonical cover comes into play.
Which is the canonical cover for a set of dependencies?
Canonical Cover A canonical coverfor Fis a set of dependencies Fc such that F logically implies all dependencies in Fc,and Fc logically implies all dependencies in F, and No functional dependency in Fccontains an extraneous attribute, and Each left side of functional dependency in Fcis unique
How to find the canonical cover in Java?
Example 2: Given a relational Schema R ( W, X, Y, Z) and set of Function Dependency FD = { W → X, Y → X, Z → WXY, WY → Z }. Find the canonical cover? Solution: Given FD = { W → X, Y → X, Z → WXY, WY → Z }, now decompose the FD using decomposition rule ( Armstrong Axiom ).
How does a canonical cover cc work in DBMS?
A canonical cover Cc is a set of all functional dependencies Fd that satisfied all the following properties as follows. Functional dependence Fd according to the rules of logic it implies all dependencies in Canonical Cover Cc.
