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I have a little problem with RE theory.
Given an alphabet {0, 1}, I have to create a regular expression that matches all string that does NOT contain the substring 111.
I’m not able to get the point, also for simplier substring like 00.
Edit: The solution must contains only the three standard operation: concatenation, alternation, kleene star, as you can see in the wiki link
Thank you.
As far as I understand, the language you want to regexify is not allowed to contain three or more consecutive 1’s. Such a regexp could be
(110|10|0*)*|1|11|0*1|0*11