Lecture
This lecture starts by explaining the absolute value of an integer, denoted by A between two bars, and how it relates to positive and negative numbers. The concept of subtraction in the set of integers is then introduced, with the unique solution for A minus B being A plus the opposite of B. The lecture provides a step-by-step explanation of why this solution exists, emphasizing the properties of addition and the importance of clear explanations in mathematical proofs. Additionally, the definition of one integer being less than or equal to another is discussed, highlighting the role of positive numbers in this comparison. Examples are given to illustrate these concepts, emphasizing the importance of understanding the abstract definitions of mathematical operations.