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MathNet 2013 Question 58

Math Olympiad Vault · MathNet 2013

Question 58

A configuration of $4027$ points in the plane, of which $2013$ are red and $2014$ blue, with no three collinear, is called Colombian. Drawing some lines divides the plane into regions. A collection of lines is good for a Colombian configuration if:
- no line passes through a point of the configuration;
- no region contains points of both colors.

Find the smallest $k$ such that every Colombian configuration of $4027$ points has a good collection of $k$ lines.