I would hazard in general that there are going to be a significant number of isomorphic regular expressions. Searching for whether anyone has looked into this, I found this exchange where the same question you pose is discussed.
http://stackoverflow.com/questions/9607062/library-to-check-if-two-regular-expressions-are-equal-isomorphic <http://stackoverflow.com/questions/9607062/library-to-check-if-two-regular-expressions-are-equal-isomorphic> [fletcher] > On May 9, 2017, at 6:06 AM, Jean-Christophe Helary > <[email protected]> wrote: > > David, > > Thank you for your reply. > >> On May 9, 2017, at 20:05, Dave <[email protected]> wrote: >> >> Parsimony aside, since the pipe defines alternative patterns, there is no >> way to create patterns like (dog|cat) using character classes. > > Hence the question "I'm wondering if [] and | are equivalent for *single > characters*". (emphasis added). > > So the question is, for any arbitrary a and b, are [ab] and a|b logically > equivalent, or are there cases for some a and b where it is not the case? > > Jean-Christophe > >> >> On Monday, May 8, 2017 at 10:10:45 PM UTC-4, Jean-Christophe Helary wrote: >> I'm wondering if [] and | are equivalent for single characters or if there >> are marginal cases where they would not be equivalent ? > > -- > This is the BBEdit Talk public discussion group. If you have a > feature request or would like to report a problem, please email > "[email protected]" rather than posting to the group. > Follow @bbedit on Twitter: <http://www.twitter.com/bbedit> > --- > You received this message because you are subscribed to the Google Groups > "BBEdit Talk" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/bbedit. -- This is the BBEdit Talk public discussion group. If you have a feature request or would like to report a problem, please email "[email protected]" rather than posting to the group. Follow @bbedit on Twitter: <http://www.twitter.com/bbedit> --- You received this message because you are subscribed to the Google Groups "BBEdit Talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/bbedit.
