Let $f: X \rightarrow Y$ be a function. Define a relation $R$ in $X$ given by $R =\{(a, b): f(a)=f(b)\} .$ Examine if $R$ is an equivalence relation.
For every $a \in X ,(a, a) \in R ,$ since $f(a)=f(a),$ showing that $R$ is reflexive. Similarly, $(a, b) \in R \Rightarrow f(a)=f(b)$ $ \Rightarrow f(b)=f(a)$ $ \Rightarrow(b, a) \in$ $R$. Therefore, $R$ is symmetric. Further, $(a, b) \in R$ and $(b, c) \in R \Rightarrow$ $f(a)=f(b)$ and $f(b)=f(c) \Rightarrow f(a)$ $=f(c) \Rightarrow(a, c) \in R ,$ which implies that $R$ is transitive. Hence, $R$ is an equivalence relation.
Let $R$ be a relation on $Z \times Z$ defined by$ (a, b)$$R(c, d)$ if and only if $ad - bc$ is divisible by $5$ . Then $\mathrm{R}$ is
If $n(A) = m$, then total number of reflexive relations that can be defined on $A$ is-
Let $R$ be a relation on a set $A$ such that $R = {R^{ - 1}}$, then $R$ is
Let $R$ be the relation in the set $N$ given by $R =\{(a,\, b)\,:\, a=b-2,\, b>6\} .$ Choose the correct answer.
Let $\mathrm{T}$ be the set of all triangles in a plane with $\mathrm{R}$ a relation in $\mathrm{T}$ given by $\mathrm{R} =\left\{\left( \mathrm{T} _{1}, \mathrm{T} _{2}\right): \mathrm{T} _{1}\right.$ is congruent to $\left. \mathrm{T} _{2}\right\}$ . Show that $\mathrm{R}$ is an equivalence relation.