Regular Languages Closed Under Subsequences

(Easy Theory is in 60 FPS now!) Here we look at the problem of showing that regular languages are closed under subsequences (i.e., a substring but doesn't have to be contiguous). The idea is to "eliminate" transitions in the initial DFA by introducing epsilon transitions for every existing transition. We also give a concrete example of this.

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▶ADDITIONAL QUESTIONS◀

1. What about "supersequences"? (i.e., all strings that include some string w in L as a subsequence)
2. What about substrings?

▶SEND ME THEORY QUESTIONS◀ ryan.e.dougherty@icloud.com

▶ABOUT ME◀ I am a professor of Computer Science, and am passionate about CS theory. I have taught over 12 courses at Arizona State University, as well as Colgate University, including several sections of undergraduate theory.

▶ABOUT THIS CHANNEL◀ The theory of computation is perhaps the fundamental theory of computer science. It sets out to define, mathematically, what exactly computation is, what is feasible to solve using a computer, and also what is not possible to solve using a computer. The main objective is to define a computer mathematically, without the reliance on real-world computers, hardware or software, or the plethora of programming languages we have in use today. The notion of a Turing machine serves this purpose and defines what we believe is the crux of all computable functions.

This channel is also about weaker forms of computation, concentrating on two classes: regular languages and context-free languages. These two models help understand what we can do with restricted means of computation, and offer a rich theory using which you can hone your mathematical skills in reasoning with simple machines and the languages they define.

However, they are not sim ... https://www.youtube.com/watch?v=2bPMta_92tI