Notes on Perverse Sheaves and Vanishing Cycles

These notes are my continuing effort to provide a sort of working mathematician’s guide to the derived category and perverse sheaves. They began as handwritten notes for David Mond and his students, and then I decided to type them for possible inclusion as an appendix in a paper. Now, however, these notes represent more of a journal of my understanding of this machinery; whenever I believe that I have understood a new, significant chunk of the subject, I put it here – so that the next time that I want to understand or use that chunk, I will only have to look in one place. Moreover, the place that I have to look will be written in a manner that I can follow easily (and that I can carry around easily). The version number indicates the month and year when I last added to this effort.