All the seminars were held online this semester because everyone were in quarantine. I don’t have a pad letting me write on it when give a live broadcast, so I prepared these slides. Using slides is faster than writing on a blackboard, so it took me only one hour to finish this talk. Some proofs are a bit long and I didn’t have enough time to prepare, so all the proofs were handwritten, very flexible. That works well.

This seminar is about homological algebra, using Joseph J. Rotman, An Introduction to Homological Algebra as our main reading material. My part is section 4.1 & 4.2, talking about semisimple rings with projective and injective modules, and von Neumann regular rings with flat modules. Somewhat easy.