Well, if you want to determine what can happen at runtime,
and rule out the cases that will not happen, all you have to
do is solve the halting problem. But you need something more
complex than a Turing Machine to do that.
That's what I was getting at - that the problem as stated in the headline was harder than, and different from, what he really needed.
But I suspect what you just described may be harder still than what he was describing in his headline. You don't always need a completely general solution, as even one that clears away a few more special cases would help. After all, the real case I outlined is non-recursive, and you don't need an oracle machine to show it. PML.