MathDB
Transitioning between admissible coloring

Source: Saint Petersburg 2016

December 11, 2016
combinatoricsColoring

Problem Statement

The cells of a square 100×100100 \times 100 table are colored in one of two colors, black or white. A coloring is called admissible if for any row or column, the number bb of black colored cells satisfies 50b6050 \le b \le 60. It is permitted to recolor a cell if by doing so the resulting configuration is still admissible. Prove that one can transition from any admissible coloring of the board to any other using a sequence of valid recoloring operations.