I meant more as how to mentally model it in a way that can get someone across the line. My assertion is that caring about undecidability is almost certainly a waste of time for most people. That said, the reason we work in small chunks is often so that we can more easily answer questions about programs.

Moving the graphical drawing and constraints over to a symbolic system also helps see how many symbols it can take to cover a simple system.

Of course, the real reason for me thinking on this is that I'm playing with FreeCAD for the first time in a long time. :D