"I think Rice's theorem is a big hammer here" It is certainly a big hammer, but as theoretical computer science tools go, it is pleasingly easy to use. Unfortu

"I think Rice's theorem is a big hammer here" It is certainly a big hammer, but as theoretical computer science tools go, it is pleasingly easy to use. Unfortunately it is pleasingly easy to use in much the same way high explosives are pleasingly easy to blow yourself up with, as it annihilates so many things that we'd rather like to keep. But, still... easy to use.