मंजिलें बड़ी जिद्दी होती हैं, हासिल कहां नसीब से होती हैं।
मगर वहां तूफान भी हार जाते हैं, जहां कश्तियां जिद्द पे होती हैं।।

Logics for this lecture:

•A relation R on set A is said to be
reflexive if $$(a, a) \in R, \forall a \in A \text{ or } aRa, \forall a \in A$$
symmetric if $$(a, b) in R \Rightarrow (b, a) \in R, \forall a, b \in A \text{ or } aRb \Rightarrow bRa, \forall a, b \in A$$
transitive if $$(a, b) \in R, (b, c) \in R \Rightarrow (a, c) \in R, \forall a, b, c \in A \text{ or } aRb \text{ and } bRc, \Rightarrow aRc, \forall a, b, c \in A$$
•If a relation is reflexive, symmetric and transitive then the relation is said to be equivalence relation.
• An important property of an equivalence relation is that it divides the set into pairwise disjoint (or mutually disjoint) subsets called equivalence classes whose collection is called a partition of the set.
• The union of all equivalence classes gives the whole set.