Learning C# 3.0

Creating Models

Humans are model-builders. We create models of the world to manage complexity and to help us understand problems we’re trying to solve. You see models all the time. Street maps are models of roadways. Globes are models of the Earth. Atomic models are models of the interaction of subatomic particles.

Models are simplifications. There is little point to a model that is as complex as the object in the problem domain. If you had a map of the United States that had every rock, blade of grass, and bit of dirt in the entire country, the map would have to be as big as the country itself. Your road atlas of the United States eschews all sorts of irrelevant detail, focusing only on those aspects of the problem domain (such as the country’s roads) that are important to solving the problem (getting from place to place). If you want to drive from Boston to New York City, you don’t care where the trees are; you care where the exits and interchanges are located. Therefore, the network of roads is what appears in the atlas.

Albert Einstein once said: “Things should be made as simple as possible, but not any simpler.” A model must be faithful to those aspects of the problem domain that are relevant. For example, a road map must provide accurate relative distances. The distance from Boston to New York must be proportional to the actual driving distance. If 1 inch represents 25 miles at the start of the trip, it must represent 25 miles throughout the trip, or the map will be unusable. ...