alt Hacker News>Every finite set of points in the Euclidean plane that is not collinear has a line that passes through exactly two of the points.
Isn't this a tautology?
The problem definition states that the set of points is in Euclidean space, which from Euclid's Axioms means we can draw a line between any two points. The set of points is defined to be not collinear, thus we cannot draw a line passing through more than two of them. This is just simple logic.
Replies
LegionMammal978 • today at 4:16 AM
"The set is not collinear" here means "there is no straight line passing through all the points simultaneously", not "there is no straight line passing through some three points".
➕ show 1 reply
That is not what was meant. Here is a better rephrasing:
Let X be a set of points not all of which are collinear. Then, there are two points a, b in X such that the line l passing through X only passes through a and b.