Section 1.1 & 1.2: Types of Relations

Exercise 1

Determine whether each of the following relations are reflexive, symmetric and transitive:

  1. Relation \(R\) in the set \(A = \{1, 2, 3, \ldots, 13, 14\}\) defined as
    \[R = \{(x, y) : 3x - y = 0\}\]

  2. Relation \(R\) in the set \(\mathbb{N}\) of natural numbers defined as
    \[R = \{(x, y) : y = x + 5 \text{ and } x < 4\}\]

  3. Relation \(R\) in the set \(A = \{1, 2, 3, 4, 5, 6\}\) as
    \[R = \{(x, y) : y \text{ is divisible by } x\}\]

  4. Relation \(R\) in the set \(\mathbb{Z}\) of all integers defined as
    \[R = \{(x, y) : x - y \text{ is an integer}\}\]

  5. Relation \(R\) in the set \(A\) of human beings in a town at a particular time given by

  1. \(R = \{(x, y) : x \text{ and } y \text{ work at the same place}\}\)
  2. \(R = \{(x, y) : x \text{ and } y \text{ live in the same locality}\}\)
  3. \(R = \{(x, y) : x \text{ is exactly 7 cm taller than } y\}\)
  4. \(R = \{(x, y) : x \text{ is wife of } y\}\)
  5. \(R = \{(x, y) : x \text{ is father of } y\}\)