Give an example of a relation. Which is Reflexive and symmetric but not transitive.
Let $A=\{4,6,8\}$
Define a relation $R$ on $A$ as
$A=\{(4,4),\,(6,6),\,(8,8),\,(4,6),\,(6,4),\,(6,8),\,(8,6)\}$
Relation $R$ is reflexive since for every $a \in A,\,(a, \,a) \in R$
i.e., $\{(4,4),(6,6),(8,8)\}\in R$
Relation $R$ is symmetric since $(a, \,b) \in R \Rightarrow(b, a) \in R$ for all $a, \,b \in R$
Relation $R$ is not transitive since $(4,6),(6,8) \in R,$ but $(4,8)\notin R$
Hence, relation $R$ is reflexive and symmetric but not transitive.
Let $P ( S )$ denote the power set of $S =\{1,2,3, \ldots, 10\}$. Define the relations $R_1$ and $R_2$ on $P(S)$ as $A R_1 B$ if $\left( A \cap B ^{ c }\right) \cup\left( B \cap A ^{ c }\right)=\varnothing$ and $AR _2 B$ if $A \cup B ^{ c }=$ $B \cup A ^{ c }, \forall A , B \in P ( S )$. Then :
If $A = \{1, 2, 3\}$ , $B = \{1, 4, 6, 9\}$ and $R$ is a relation from $A$ to $B$ defined by ‘$x$ is greater than $y$’. The range of $R$ is
${x^2} = xy$ is a relation which is
Let $A = \{1, 2, 3\}, B = \{1, 3, 5\}$. If relation $R$ from $A$ to $B$ is given by $R =\{(1, 3), (2, 5), (3, 3)\}$. Then ${R^{ - 1}}$ is
Show that the relation $R$ in $R$ defined as $R =\{(a, b): a \leq b\},$ is reflexive and transitive but not symmetric.