MathDB
Integers on real axis

Source: Turkish NMO 1996, 3. Problem

July 31, 2011
combinatorics proposedcombinatorics

Problem Statement

Let nn integers on the real axis be colored. Determine for which positive integers kk there exists a family KK of closed intervals with the following properties: i) The union of the intervals in KK contains all of the colored points; ii) Any two distinct intervals in KK are disjoint; iii) For each interval II at KK we have aI=k.bI{{a}_{I}}=k.{{b}_{I}}, where aI{{a}_{I}} denotes the number of integers in II, and bI{{b}_{I}} the number of colored integers in II.