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I'm stumped on how you would describe a language which is a* except for aa, so the following is acceptable:

a
aaa
aaaa
aaaaa
...

It's for part of the below DFA enter image description here

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Hint: A word consisting of $n \neq 2$ many $a$s either consists of zero $a$s, or of a single $a$, or of at least three many $a$s.

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  • $\begingroup$ ohhh so (empty) + a + aaaa* would cover those $\endgroup$ Oct 14 '21 at 8:03
  • $\begingroup$ Right, that's the solution. $\endgroup$ Oct 14 '21 at 8:07

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