Uploads and updates.

I created a couple of modules in Canvas. Two are links to material in the left margin and from previous year's version. One is what I thought would be a short note on the first lecture, but which became quite 14 slides. If you don't want to go to Canvas, you find the slideset at this direct link.

I have taken as "null hypothesis" that students want Canvas, but let us discuss that in the first lecture.