An Inquiry-Based Approach to Abstract Algebra Dana C. Ernst, PhD Northern Arizona University Fall 2016 c 2016 Dana C. Ernst. Some Rights Reserved. This work is licensed under the Creative Commons Attribution-Share Alike 3.0 United States License. You may copy, distribute, display, and perform this copyrighted work, but only if you give credit to Dana C. Ernst, and all derivative works based upon it must be published under the Creative Commons Attribution-Share Alike 4.0 International Li- cense. Please attribute this work to Dana C. Ernst, Mathematics Faculty at Northern Arizona University,
[email protected]. To view a copy of this license, visit https://creativecommons.org/licenses/by-sa/4.0/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, Cali- fornia, 94105, USA. cba Here is a partial list of people that I need to thank for supplying content, advice, and feedback. • Ben Woodruff • Josh Wiscons • Dave Richeson • Nathan Carter • AppendixB: The Elements of Style for Proofs is a blending of work by Anders Hen- drickson and Dave Richeson. • Dave Richeson is the original author of AppendixC: Fancy Mathematical Terms and AppendixD: Definitions in Mathematics. Contents 1 Introduction4 1.1 What is Abstract Algebra?............................4 1.2 An Inquiry-Based Approach...........................4 1.3 Rules of the Game.................................5 1.4 Structure of the Notes...............................6 1.5 Some Minimal Guidance.............................6 2 An Intuitive Approach to Groups8 3 Cayley Diagrams 15 4 An Introduction to Subgroups and Isomorphisms 25 4.1 Subgroups..................................... 26 4.2 Isomorphisms................................... 29 5 A Formal Approach to Groups 34 5.1 Binary Operations................................