Determine if it is possible to choose nine points in the plane such that there are $n=10$ lines in the plane each of which passes through exactly three of the chosen points. What if $n=11$?
Source: MOP 2005 Homework - Red Group #12
Tags: combinatorics unsolved, combinatorics
Determine if it is possible to choose nine points in the plane such that there are $n=10$ lines in the plane each of which passes through exactly three of the chosen points. What if $n=11$?