Actually, what I'm trying to resolve is the "receivers regex can accept a superset of the emitters pattern generator" question. Specifically, whether that is equivalent to the halting problem or not.

As I said in another note, I believe that DFAs require a memory strip to be Turing-complete, and thus analysis of regexps doesn't run into the halting problem. But I'm not certain of that, and my last Comp. Sci. course was very long ago.

Resolving to canonical form is a good first step, but it's not entirely clear how to algorithmically determine that, for example, aaaab?aaaa is a subset of aaaaab*aaaaa. That one took a moment to prove and double-check in my head, and it's a *really* trivial case compared to some I'd like to verify.

Brain-achingly,

Mickey.