I have lecture notes that I'd like to turn into a book one day. Give me a day or soI have not yet had time to adapt to my new TeX system, and I will post a link the drawings done via ps-tricks do not yet come out as planned. In addition, there are gaps and mistakes that I have not yet had time to fill and correct (the chapter on composition should be essentially correct and complete, however). In any case, the relevant sectionspresent set of notes, for the time being, can be found here. Comments and corrections are welcome.