bw colorings in a 4x4 table after n steps
Source: JBMO 2008 Shortlist C4
October 14, 2017
JBMOcombinatoricsColoring
Problem Statement
Every cell of table is colored into white. It is permitted to place the cross (pictured below) on the table such that its center lies on the table (the whole fi gure does not need to lie on the table) and change colors of every cell which is covered into opposite (white and black). Find all such that after steps it is possible to get the table with every cell colored black.