Show that each of the relation $R$ in the set $A=\{x \in Z: 0 \leq x \leq 12\},$ given by $R =\{( a , b ): a = b \}$ is an equivalence relation. Find the set of all elements related to $1$ in each case.
$R =\{( a , b ): a = b \}$
For any element a $\in A,$ we have $(a,\, a) \in R,$ since $a=a$
$\therefore R$ is reflexive.
Now, let $(a, b) \in R$
$\Rightarrow a=b$
$\Rightarrow b=a \Rightarrow(b, a) \in R$
$\therefore R$ is symmetric.
Now, let $(a, b) \in R$ and $(b, c) \in R$
$\Rightarrow a=b$ and $b=c$
$\Rightarrow a=c$
$\Rightarrow(a,\, c) \in R$
$\therefore R$ is transitive.
Hence, $R$ is an equivalence relation.
The elements in $R$ that are related to $1$ will be those elements from set $A$ which are equal to $1$
Hence, the set of elements related to $1$ is $\{1\}$.
The minimum number of elements that must be added to the relation $R =\{( a , b ),( b , c )$, (b, d) $\}$ on the set $\{a, b, c, d\}$ so that it is an equivalence relation, is $.........$
Let $R$ be the relation defined in the set $A=\{1,2,3,4,5,6,7\}$ by $R =\{(a, b):$ both $a$ and $b$ are either odd or even $\} .$ Show that $R$ is an equivalence relation. Further, show that all the elements of the subset $ \{1,3,5,7\}$ are related to each other and all the elements of the subset $\{2,4,6\}$ are related to each other, but no element of the subset $\{1,3,5,7\}$ is related to any element of the subset $\{2,4,6\} .$
Let $r$ be a relation from $R$ (set of real numbers) to $R$ defined by $r = \{(a,b) \, | a,b \in R$ and $a - b + \sqrt 3$ is an irrational number$\}$ The relation $r$ is
Show that the relation $\mathrm{R}$ in the set $\mathrm{Z}$ of integers given by $\mathrm{R} =\{(\mathrm{a}, \mathrm{b}): 2$ divides $\mathrm{a}-\mathrm{b}\}$ is an equivalence relation.
Which one of the following relations on $R$ is an equivalence relation