Machine-translated by Google. Questions are authored in English.
Top

Discussion

Let \(X = \{a_1, a_2, a_3, \ldots, a_n\}\) be a set consisting of \(n\) elements. The relation \(R = \{(a_1, a_1), (a_2, a_2), (a_3, a_3), \ldots, (a_n, a_n)\}\) on the set \(X\) is

  • A.reflexive, symmetric but not transitive
  • B.reflexive, transitive but not symmetric
  • C.transitive, symmetric but not reflexive
  • D.reflexive, symmetric and transitive
  • E.reflexive, not symmetric and not transitive

Answer: D

The relation is reflexive, symmetric and transitive.

\(R\) contains exactly the pairs \((a_k, a_k)\), so it is the identity relation on \(X\). It is reflexive because every \((a_k, a_k)\) is in \(R\). It is symmetric because the only pairs are of the form \((a, a)\), and reversing them gives the same pair. It is transitive because \((a, b)\) and \((b, c)\) in \(R\) force \(a = b = c\), so \((a, c) = (a, a)\) is in \(R\).

The identity relation is therefore an equivalence relation, and every option that denies one of the three properties is wrong.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.