Episode 9: Regex- Making the lazy even lazier

This week we finally covered regular expressions. I had never used them before, nor known how they worked, but I had heard from my programming friends that it was insanely useful and easy to use; therefore I was very excited to learn about how to be as lazy as possible.

Fortunately, things did seem quite easy, as language operations just seemed like sets that we learned in 165, and regular expression examples were cool. It was like learning a complete language, and material like + (or), and * (Kleene stars) were not too difficult to learn.

The most difficult part of this (thus far) was proving equality of languages.
Not only did I have to prove that a string \in L1 (a language) implied that a string was in a language denoted by a certain regular expression, but I had to prove it the OPPOSITE way. The first proof was quite simple, but the reverse direction was a lot more difficult to comprehend (and the example in the txtbook did not help much in my understanding). Anyway, hoping to do well in this section since I do understand about 80% of the material and could do more with studying.