[sacado2]

> Curious: has your knowledge of the halting problem ever actually saved you time or effort in your work? If so, how?

Not OP, but I'm working a lot with ontologies. Some ontologies representations are undecidable, while other languages are not very expressive but can be manipulated in polynomial time. Had I not known that, I would still be like "crap, why does it take so long? I must have a bug somewhere, maybe I should switch to C".

> AI and ML are being advanced more by people with more knowledge of linear algebra and statistics than computer science.

Just answered OP about that, but actually, symbolic AI is pure computer science. It does not get as much publicity as ML currently, but believe me, it's everywhere: at the core of almost all package managers, like debian's apt-get or maven, at the core of most advanced static code analyzers, etc.