Peter Krautzberger · on the web

Red workbook, p7


red workbook, p7
Red Workbook, p.7




Same lecture, new chapter. This is the first of two pages on the basics of thick sets.

"Thick" is an odd notion. It always seems a little made up to me, something stated after the fact (after asking "what does a set look like that covers a left ideal?"). On the other hand, for , I can imagine that the notion "a set that contains arbitrarily long intervals" might actually come up independently of ultrafilters. However, I don't know the history of the notion, so I'm probably wrong here (if you know anything about this, please leave a comment).

A technical note. I realized that using the section heading "partial translation" was a bit misleading; as would be "augmented/corrected translation". In fact, I do both -- leave some things out (negligible comments etc), clear up the layout, and add corrections (e.g. instead of ). So I will just call it "translation" from now on.