TOT 1998 Spring OS3 max colours to pain 8x8 chessboard
Source:
May 11, 2020
ChessboardColoringcombinatorics
Problem Statement
What is the maximum number of colours that can be used to paint an chessboard so that every square is painted in a single colour, and is adjacent , horizontally, vertically but not diagonally, to at least two other squares of its own colour?(A Shapovalov)