MathDB
TOT 1998 Autumn AJ2 8x8 square , blue, 2x1dominoes

Source:

May 11, 2020
combinatoricsColoringcombinatorial geometryTiling

Problem Statement

John and Mary each have a white 8×88 \times 8 square divided into 1×11 \times 1 cells. They have painted an equal number of cells on their respective squares in blue. Prove that one can cut up each of the two squares into 2×12 \times 1 dominoes so that it is possible to reassemble John's dominoes into a new square and Mary's dominoes into another square with the same pattern of blue cells.
(A Shapovalov)