Talk:Necessary and sufficient
"A circle (in the plane) is usually defined as a curve such that its points all have the same distance from a given point" — a bit problematic; say, half a circle, is it also a circle? It IS "a curve such that its points all have the same distance from a given point", isn't it? Boris Tsirelson 10:05, 2 February 2010 (UTC)
- True, of course. I wanted to keep this colloquial, and there this distinction is usually not made. (It holds for both characterizations.) And since I did not think of the formulation I found now ...
- By the way: Boris, do you think (agree) that this topic is worth a page (for non-mathematicians) like this?
- --Peter Schmitt 10:36, 2 February 2010 (UTC)