What is a Set? • A set is a collection of well-defined objects or elements. • Elements are written inside curly braces { }. • Example: A = {1, 2, 3, 4, 5} • Each element appears only once.
Ways to Represent a Set 1. Roster Form: A = {2, 4, 6, 8} 2. Set-builder Form: A = {x | x is an even number less than 10} • Both describe the same set but in different ways.
Types of Sets • Empty Set: No elements (Ø or {}). • Finite Set: Countable elements. • Infinite Set: Uncountable elements. • Subset: Every element of one set belongs to another.
Venn Diagrams • Visual representation of sets using circles. • Overlapping areas show common elements (intersections). • Helps visualize relationships between sets.
Set Operations • Union (A ∪ B): Elements in A or B or both. • Intersection (A ∩ B): Common elements in both. • Difference (A - B): Elements in A not in B. • Complement (A'): Elements not in A.
Example Problem If A = {1, 2, 3} and B = {3, 4, 5}: • A ∪ B = {1, 2, 3, 4, 5} • A ∩ B = {3} • A - B = {1, 2}
Applications of Set Theory • Used in computer science for data organization. • Helps in probability and statistics. • Used to group and compare different categories. • Common in logic, AI, and data analysis.
Summary • A set is a group of distinct elements. • Represented using curly braces {}. • Visualized using Venn diagrams. • Key operations: Union, Intersection, Difference, Complement.