Algebraic Topology - 4 - Categories and Functors

Don't watch this video. Go read about this somewhere else. Category theory is essentially the black hole of math. We could go and talk about this stuff forever and never get to apply it. I cut this video short because I think you get the idea of what is going on. I'm going to develop these things in more detail every couple of lectures as we go. (one of the reasons why we like to teach new PhD students Algebraic Topology is precisely because it teaches people how to become a user of category theory.) Go follow Emily Reihl on twitter and look for her explanation of things. Also, take a look at Awodey's videos on category theory.