This class will cover non regular languages, and context free grammars.


Non Regular Languages

Recall the Pigeonhole Principle:

  • pigeonholes pigeons
  • at least one pigeonhole with no pigeon

And the term Vacuously True:

  • true because there are no elements in

And Superscripts:

These are all important because they help us to understand the concept of Non Regular Languages.

Non regular languages are languages that cannot be described by a regular expression. This is because regular expressions are limited in their ability to describe languages that have a “memory” or “state”.