MathDB
two sets

Source: Vietnam TST 2008, Problem 6

September 5, 2008
functionalgebrapolynomialgroup theorycombinatorics proposedcombinatorics

Problem Statement

Consider the set M={1,2,,2008} M = \{1,2, \ldots ,2008\}. Paint every number in the set M M with one of the three colors blue, yellow, red such that each color is utilized to paint at least one number. Define two sets: S1={(x,y,z)M3  x,y,z have the same color and 2008(x+y+z)} S_1=\{(x,y,z)\in M^3\ \mid\ x,y,z\text{ have the same color and }2008 | (x + y + z)\}; S2={(x,y,z)M3  x,y,z have three pairwisely different colors and 2008(x+y+z)} S_2=\{(x,y,z)\in M^3\ \mid\ x,y,z\text{ have three pairwisely different colors and }2008 | (x + y + z)\}. Prove that 2S1>S2 2|S_1| > |S_2| (where X |X| denotes the number of elements in a set X X).