https://www.quantamagazine.org/mathematician-disproves-hedetniemis-graph-theory-conjecture-20190617/?fbclid=IwAR2du3Jwz17kOaXeZHlILgtbrWF3SwocJt-TVR8gqkbNa7uC47qiFZOQ3jA
A 53-Year-Old Network Coloring Conjecture Is Disproved | Quanta Magazine
Dec 23, 2019 - In just three pages, a Russian mathematician has presented a better way to color certain types of networks than many experts thought possible.
a 53year oldnetwork coloring