11. The Snake Lemma and its friends

In this lecture we learn how to "diagram chase". This is a particularly fun and relaxing method of proof, since it is basically impossible to go wrong (i.e. if the proof doesn't work, the theorem is false.)

Fun fact:

After a hard day's work, many mathematicians like to open up the fridge, grab a beer, then kick back and chill on the sofa while diagram chasing. 🤓