Prove why it cannot be answered using relational algebra. •Consider the followin

Question

Prove why it cannot be answered using relational algebra.

•Consider the following relation R containing generation information.
R (name1, name2, relationship)
•For example, a tuple <Davis, Mary, Father> means David is the Father of Mary; a tuple <Mary, Smith, Mother> means Mary is the Mother of Smith; etc.
•Suppose we are interested in finding all the descendants of David. (from the two example tuples, Mary and Smith are all descendants of David) Such a query could not be expressed using relational algebra. Prove why it cannot be answered using relational algebra.

Explanation / Answer

Solution:

Transitive closure is the only limitation relational algebra has.

and as per the given tuples <Davis, Mary, Father> and <Mary, Smith, Mother> only transitive closure can be performed to extract all the descendants of David. That is why the problem cannot be solved using relational algebra.

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