[pjc50]

Yes, humans are incredible at reverse engineering. My point was about specification, and what happens if you have only a specification and no implementation. Because that's more closely analogous to the mathematical situation, where you're manipulating the specification.

You said:

> because programs can't work without being specified.

.. what I think you may have meant was "can't work without being implemented", because your subsequent comments are all about implementation.

> Undefined behavior isn't a feature

Yes it is, it's a feature of the C specification.

This is where a whole load of pain and insecurity comes from, because as you say the implementations must do something when encountering undefined behavior, and people learn what usually happens, then an improvement is made to the optimizer which changes the implementation.