Relations and Functions (सम्बन्ध एवं फलन) -
1. Cartesian Product (कार्तीय गुणन)
If A = {a, b} and B = {1, 2}
Then A × B = {(a,1), (a,2), (b,1), (b,2)}
2. Relation (सम्बन्ध)
A relation R from A to B is a subset of A × B
3. Types of Relations (सम्बन्ध के प्रकार)
Reflexive Relation (प्रतिवर्ती):
(a,a) ∈ R for all a ∈ A
Symmetric Relation (सममित):
If (a,b) ∈ R ⇒ (b,a) ∈ R
Transitive Relation (सांक्रामक):
If (a,b) ∈ R and (b,c) ∈ R ⇒ (a,c) ∈ R
Equivalence Relation:
Reflexive + Symmetric + Transitive
4. Function (फलन)
f : A → B
y = f(x)
5. Types of Functions (फलनों के प्रकार)
One-One Function (Injective):
f(x₁) = f(x₂) ⇒ x₁ = x₂
Onto Function (Surjective):
Range = Co-domain
Bijective Function:
One-One + Onto
6. Composite Function (संयुक्त फलन)
(f ∘ g)(x) = f(g(x))
7. Identity Function (परिचय फलन)
I(x) = x
8. Inverse Function (प्रतिलोम फलन)
f⁻¹(x)
f(f⁻¹(x)) = x
f⁻¹(f(x)) = x