I'm with Michel on this one:
Just a remark about "abutment": it translates the French "aboutement", with a rather different meaning than "aboutissement". The latter is closer to the "ending" (of some process; with possibly a little shade of "fatality" in it).
The two words are related, and I don't know whether the mathematical idea behind makes "abutment" good, or even better, but I just wanted to mention the difference.
Not a single abutment in any of the following YouTube videos posted by their proud aboutisseurs. http://www.youtube.com/results?search_query=aboutissement&search_type= Evidently G needed a word with the sense of "limit" or "completion" that didn't overload terms that already had technical meanings in that context while itself having a technical ring to it, which "aboutissement" seems to do nicely in French. Something like "terminus" might serve this purpose in English. An abutment is an engineering construct for butting two things together, often in the context of bridges, whether over a river or between teeth, and seems quite unsuitable for this purpose. Vaughan