Comment by deadgrey19

What I'm discussing here is the general concept of modelling your program formally before writing it (as per the article). What I'm arguing is that this type of approach is only possible for a certain set of applications which take the form of y = f(x), where f(x) is some type of data transformation /computation operation (e.g. calculate the GCD of these ints, find the shortest path through a given graph, sort this set etc). There's another set of applications which I/O bound, are very important, and yet, the "computation" that they preform is limited to none. These applications are rooted in, and bounded by system parameters, like understanding how disks work, how network cards work, how CPUs work etc. This is an optimisation problem, but not one that can be modelled mathematically (in any reasonable way) because of the vast complexities of the system. Building a TLA+ "proof" of this system will reduce trivially to x = x, and yet, the system is still important, and difficult to write well.