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Quiz: Regular Expressions

5 questionsNo time limitPass: 60%+10 XP on first pass

Formal regular expressions (union, concatenation, star), writing regex for typical exam languages, Thompson's construction from regex to ε-NFA, closure properties of regular languages, identities, and how textbook regex relates to the regex in Python, Java and JavaScript.

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  1. Question 1

    Which regex describes binary strings ending in 01?

  2. Question 2

    What does ab* mean?

  3. Question 3

    Which operation are regular languages NOT closed under?

  4. Question 4

    Which regex describes strings with no two consecutive 1s (verified in the demo)?

  5. Question 5

    Why should you avoid patterns like (a+)+$ on user input?