Re the graph quality: I'm REALLY sorry and I have to apologize to Stuart for the poor quality of images - it's kind of my fault... When I typesetted the final version of the proceedings, they were in A5 format, but on A4 page. We sent it to the printing company and they ran it through some program that cropped the pages to A5. Alas, this program also terribly compressed the images and I didn't check it carefully before letting them print it. So this is it... Once more sorry about that.
The only thing I can do is to fix it in this electronic version - will be done asap.
Anyway, thanks Stuart for your great talk!
The link now points to the fixed proceedings (better image resolution). Sorry once again. Jan