The reason I was guessing at is that they have a lot of data to validate based on a complex regex and were considering using another faster regex as a precheck to save on processing.

If this was the case then it's to prove that the precheck won't reject anything that the main check would allow.

In reply to Re^2: Comparative satisfiability of regexps. by Molt
in thread Comparative satisfiability of regexps. by Meowse

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