Regular Expressions (Regexes), what are they?

Here we look at and define regular expressions, which allow us to describe, formally, what a language is. They are defined using three "base" cases (empty string, empty set, and a single character), and three "inductive" cases (union, concatenation, and star).

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▶ADDITIONAL QUESTIONS◀
1. What other operators can be included that can be achieved from union, concatenation, and star?

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I am a professor of Computer Science, and am passionate about CS theory. I have taught over 12 courses at two different universities, including several sections of undergraduate and graduate theory-level classes.

[jamespottex]

I don't know why so less likes even though lectures are awesome!!

[haililiang]

Thank you so much for your explanation. I am start wondering how my professor make a 6 minute video contents to an hour class time..

[agnishom]

Are you planning to make a video about Brozowski derivatives?