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A prime number and its same-colored multiples

Source: 2021 Iberoamerican Mathematical Olympiad, P1

October 20, 2021
setprime numbersnumber theory

Problem Statement

Let P={p1,p2,,p10}P = \{p_1,p_2,\ldots, p_{10}\} be a set of 1010 different prime numbers and let AA be the set of all the integers greater than 11 so that their prime decomposition only contains primes of PP. The elements of AA are colored in such a way that:
[*] each element of PP has a different color, [*] if m,nAm,n \in A, then mnmn is the same color of mm or nn, [*] for any pair of different colors R\mathcal{R} and S\mathcal{S}, there are no j,k,m,nAj,k,m,n\in A (not necessarily distinct from one another), with j,kj,k colored R\mathcal{R} and m,nm,n colored S\mathcal{S}, so that jj is a divisor of mm and nn is a divisor of kk, simultaneously.
Prove that there exists a prime of PP so that all its multiples in AA are the same color.