Theory of Computation #6: Regular Expression Examples

In this video we look at some examples to convert a problem to the corresponding regular expressions. It is very important to be able to write a regular expression for any problem/language given. This is the first step before attempting to make a finite state machine, which we would look at in the next video.

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Correction: At 9:18, the regex is incomplete as it does not account for cases with less 1's which do not need both 0's. The correct regular expression is:
0*(ε+1)0* + 0*(ε+1)00*(ε+1)0* + 0*(ε+1)00*(ε+1)00*(ε+1)0*

[bro]

1:44 isn't phi the same as phi*, also epsilon is a string and phi and phi* are sets so wouldn't that be incorrect