MathDB
Labelling the intersection points of lines

Source: Greek national M.O. 1995, Final Round, problem 4

November 20, 2011
modular arithmeticcombinatorics unsolvedcombinatorics

Problem Statement

Given are the lines l1,l2,…,lkl_1,l_2,\ldots ,l_k in the plane, no two of which are parallel and no three of which are concurrent. For which kk can one label the intersection points of these lines by 1,2,…,k−11, 2,\ldots , k-1 so that in each of the given lines all the labels appear exactly once?
Back to ProblemsView on AoPS