[sinkasapa]

That is a hard question because there are so many ways that one can understand regex. I learned how to read and use them using Unix tools like sed, but I think that my path to starting to understand them probably began with papers like "Regular Expression Matching Can Be Simple And Fast" by Russ Cox (https://swtch.com/~rsc/regexp/regexp1.html), well after feeling like I was pretty good at using them.

Then, as an expert in linguistic morphology, I started learning about things like subregular languages, as talked about in works such as Aural Pattern Recognition Experiments and the Subregular Hierarchy, by Rogers and Pullum (https://www.cs.earlham.edu/~jrogers/JoLLI.pdf). And I continue to wonder what the relationship is between these classes of languages and word formation.