University of Calgary

# Hedetniemi's Conjecture-a survey

## Abstract

What is the chromatic number of the product of two graphs? The conjecture of Hedetniemi [1], which is more than 30 years old, is: $$\chi(\fract{G}\times \fract{H})=\min\{\chi({\fract G}),\chi({\fract H})\}.$$ This survey article deals with several ramifications of this rather innocent looking question.