[edited the formulation in Q3]

After rereading the answer in "what is the correct terminology..." I notice that I did not really realized the contents of one comment, which even backed my own insecurity, that this answer was in fact not at the point: because in my question I ask for a power series problem and the answer is for a polynomial, which is then not simply compatible with my question.

I'd not taken this additional comment really into account then, and had "accepted" the answer. But I stumble across this now again and think, it would possibly be good to "re-open" the question. But perhaps, there would be no correct answer as well...

Q:

1. what do you think, do I have this conceptually correct now?
2. is it fair/not fair to "un-accept"?
3. Is it at all worth that effort (it could also contain a bit uneasyness for the original answerer)?
4. ... and only if all this is "yes", is this possible?
• This is (to some extent) related: Is it rude to change which answer you accept? – Martin Sleziak Oct 17 '12 at 12:02
• Thanks, @Martin, that makes it easier. Also I think now the best thing is to simply post a question to the answerer in a comment (what I've done just now, well it'd have been the simplest thing at the beginning...) – Gottfried Helms Oct 17 '12 at 12:09