This isn't exactly a Perl question, but Perl gurus do regexps better than anyone else I know, so I humbly request your wisdom.

The challenge: given two regexps A and B, determine (ideally in polynomial time) whether all strings that match A will also match B.

The motivation: to determine whether a process whose output is characterized by regexp A can guarantee to correctly drive a process whose input is characterized by regexp B.

The details: mildly crippled subsets of regexp are acceptable, if full-strength regexps make the problem computationally intractable or impossible. Execution time is not a huge issue; the regexps in question will be short, and the evaluation will be done at design time rather than at runtime (thus "ideally in polynomial time" above).

Thanks much!

Mickey.

In reply to Comparative satisfiability of regexps. by Meowse

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