Math Noes

Math notes part, including notes of classes and of summary by myself. Maybe the writing is not beautiful, but I asure that would be professional, mainly for my own reading so it will not be friendly to everyone, necessary knowledge always be omitted.

■   Slides for my seminar of homological algebra
         ◇ May 22, 2020  ◇ Reading time: 1 minute  ◇ Summary: Section 4.1 & 4.2 of Rotman’s book