n persons, each of them speaking at most 3 languages
Source: 2011 Romania JBMO TST 1.5
June 1, 2020
combinatorics
Problem Statement
Consider persons, each of them speaking at most languages. From any persons there are at least two which speak a common language.
i) For , exhibit an example in which no language is spoken by more than two persons.
ii) For , prove that there exists a language which is spoken by at least three persons