Lecture
This lecture covers commutative groups, Euler's Totient Function, and Cartesian products. The instructor explains the concept of commutative groups and provides examples to illustrate the properties of different sets. The lecture also delves into Euler's Totient Function, defining it as the number of positive integers that are relatively prime to a given integer. Additionally, the concept of Cartesian products is introduced, showcasing how sets are combined to form a new set with a defined binary operation. Through exercises and examples, students explore the application of these concepts in group theory.