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A comment on Is there a regular expression to detect a valid regular expression?. Parent comment

Re:Is there a regular expression to detect a valid regular e... by morelisp on Sunday September 08, 2019 @12:08PM (#20911359)
An analogous problem for this representation would be detecting transitions to undefined states, or ambiguous (duplicate) transitions.
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Re:Is there a regular expression to detect a valid regular e... by tgv on Monday September 09, 2019 @03:17AM (#20915907)
I didn't verify it, but my intuition says that can't be done with a CFG; it seems at least context-sensitive.
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