Based on the discussion on 23 Sep 2024, the input and output of a class should be structured based on diagrams. this means the i/o of each function should interact with the i/o of other functions in a class. Then those interactions combined define an entity. This is the same idea as personality. People have different characteristics but all of them combined define the personality of a person. This is the main challenge in design: building small elements in such a way that they can be combined into one unified entity. For example, there are different properties in a car. However, all those properties should be designed in connection to all other elements. It’s not possible to design the light of the car and put it aside, then design the overall shape and put the design aside and start designing another part of the car. Instead, all of it should be designed interactively. That is the main challenge of designing.
So the next task is to construct that idea mathematically so that different functions (i.e. properties) of an object interact with each other.