Problem

Source: Iranian TST 2021, second exam day 2, problem 3

Tags: set theory, combinatorics, graph theory, Coloring



Prove that we can color every subset with $n$ element of a set with $3n$ elements with $8$ colors . In such a way that there are no $3$ subsets $A,B,C$ with the same color where : $$|A \cap B| \le 1,|A \cap C| \le 1,|B \cap C| \le 1$$ Proposed by Morteza Saghafian and Amir Jafari