I see it as the crossover between approaches amenable to static order and iteration, vs those that demand constraint optimization. This is a recurring problem

I see it as the crossover between approaches amenable to static order and iteration, vs those that demand constraint optimization. This is a recurring problem in programming, because if you code towards the optimal result, you end up making a static, linearized computation that doesn't need further configuration. But if your goal is to provide interfaces and automation, you are tasked with a constraint problem, where you have multiple potential solutions and you either have to filter them down to a single unambiguous result, or find a heuristic that defines the "best one". The problem occurs with type systems, graphical layout, multi-body physics simulation, dependency management and a host of other things. I consider it the most unaddressed subject in CS because it's so relevant to applications and yet industry continually reinvents it in terms of a bespoken algorithm for that one application. And depending on what you're doing, you end up biasing to one or the other method first: a small, well-defined problem only needs the computer to do "brute" things, while a problem dependent on the computer managing the complexity of the problem needs it to find and correct errors.