MathDB

Several

good

points, several

bad

points and several segments are drawn in the plane. Each segment connects a

good

point and a

bad

one; at most

100

segments begin at each point. We have paint of

200

colors. One half of each segment is painted with one of these colors, and the other half with another one. Is it always possible to do it so that every two segments with common end are painted with four different colors? (M. Qi, X. Zhang)

Problem Statement