Problem 7 of Second round - "multicolored" figures
Source: VI International Festival of Young Mathematicians Sozopol, Theme for 10-12 grade
December 19, 2019
combinatoricstableChessboardColoring
Problem Statement
A corner with arm is a figure made of unit squares, such that 2 rectangles x are connected to two adjacent sides of a square x , so that their unit sides coincide.
The squares or a chessboard x are colored in 15 colors. We say that a corner with arm 8 is “multicolored”, if it contains each of the colors on the board. What’s the greatest number of corners with arm 8 which could be “mutlticolored”?