Injectivity and Surjectivity

This lecture covers the concepts of injectivity, surjectivity, and bijectivity in mathematical functions. It explains that a function is injective if each element in the domain maps to a unique element in the codomain, while a function is surjective if every element in the codomain has at least one pre-image in the domain. The lecture also discusses bijective functions, which are both injective and surjective, and introduces the composition of functions. Various examples and properties of injective, surjective, and bijective functions are explored.