Lecture
This lecture introduces the concept of abbreviated calculation through restoration and comparison, focusing on the study of structures and operations. It covers the definition and study of structures, the study of operations, and the comparison of sets. The lecture also delves into the unique properties of sets, such as subsets, empty sets, and pairs. Examples are provided to illustrate these concepts, along with discussions on sets that contain themselves and the equality of sets. The lecture concludes with a detailed explanation of how to define quantities and establish equality between sets.