Set theory might seem almost mundane in many cases, but it's really powerful to express certain solutions in a very concise way. I've refactored code into much

Set theory might seem almost mundane in many cases, but it's really powerful to express certain solutions in a very concise way. I've refactored code into much simpler code by just thinking about it in terms of set manipulation, vastly reducing the number of classes/tables necessary. Operations became self-explanatory (it's "just a set"). It also gives you a good foothold to realize whether the solution works or not into the future, a bit of a barebones formalism. You get to play with it in math terms before writing any code. This particular refactoring became the only thing in the codebase that didn't need to change as new requirements came along.