This will be a series of posts to support the course Abstract Mathematics that I am giving this year.
The course uses the study guide "Abstract mathematics" by M. Anthony (MT2116, 2790116), 2011. There is something about this guide that I don't like. Its review will be given later.
Boxes-and-balls (or pigeonhole) principle
Equivalence relation explained
Division of one integer by another, with remainder
Review of "Abstract Mathematics" by M. Anthony