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). <br /><br />Contribute:<br />Patreon: <a href="https://www.patreon.com/easytheory" target="_blank" rel="nofollow">https://www.patreon.com/easytheory</a><br />Discord: <a href="https://discord.gg/SD4U3hs" target="_blank" rel="nofollow">https://discord.gg/SD4U3hs</a><br /><br />Merch:<br />Language Hierarchy Apparel: <a href="https://teespring.com/language-hierarchy?pid=2&cid=2122" target="_blank" rel="nofollow">https://teespring.com/language-hierarchy?pid=2&cid=2122</a><br />Pumping Lemma Apparel: <a href="https://teespring.com/pumping-lemma-for-regular-lang" target="_blank" rel="nofollow">https://teespring.com/pumping-lemma-for-regular-lang</a><br /><br />If you like this content, please consider subscribing to my channel: <a href="https://www.youtube.com/channel/UC3VY6RTXegnoSD_q446oBdg?sub_confirmation=1" target="_blank" rel="nofollow">https://www.youtube.com/channel/UC3VY6RTXegnoSD_q446oBdg?sub_confirmation=1</a><br /><br />Gold Supporters: Anonymous (x1), Micah Wood, Ben Pritchard<br />Silver Supporters: Timmy Gy<br />Supporters: Yash Singhal <br /><br />▶ADDITIONAL QUESTIONS◀<br />1. What other operators can be included that can be achieved from union, concatenation, and star?<br /><br />▶SEND ME THEORY QUESTIONS◀<br />[email protected]<br /><br />▶ABOUT ME◀<br />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.<br />...<br /><a href="https://www.youtube.com/watch?v=7phPFEMcfEs" target="_blank" rel="nofollow">https://www.youtube.com/watch?v=7phPFEMcfEs</a>