Introduction

Welcome to the regular expressions/DFA/NDFA online exercises!

This package enables you to create regular expressions and automata to accept a given language, and then see where you went wrong. There are questions asking for regular expressions, DFAs, and NDFAs. You enter a solution to the posed question, the program figures out if it is correct, and tells you so.

• Click a link under the section headings to see the question applet and enter your solution, then press "Submit" when you're done.
• If you're wrong, the applet will tell you which strings your regular expression accepts that it shouldn't, and those that it should accept but doesn't. Change your entry and try again.
• The navigation buttons can jump to the next question, previous, give you a brief hint, show you the answer (once you've tried a couple of times), or show you the instructions page.
• Press the Syntax button for details on how to enter your answer.
• Click on a section title to see an introduction to a section, including notes on the syntax required for entering your solutions.