On Tue, 07 May 2013 09:05:38 -0700, Barry Schwarz <firstname.lastname@example.org> wrote:
>On 07/05/2013 08:48, William Elliot wrote: >> Let C be a collection of n points with the property that >> any line L with two points of C on it, has a third point >> of C on it. >> >> How is it that C is collinear, ie all points of C are >> on a single line? > >The assertion is not true if points are allowed to be coincident.
But the way the language is used in this sort of context, "n points" _means_ n distinct points.
Really. You could give the same objection to "two points determine a line"...