A SURVEY ON HEDETNIEMI'S CONJECTURE
Xuding Zhu · Taiwanese Journal of Mathematics · 1998
More than 30 years ago, Hedetniemi made a conjecture which says that the categorical product of two n-chromatic graphs is still n-chromatic. The conjecture is still open, despite many dierent approaches from dierent point of views. This article surveys methods and partial results; and discuss problems related to or motivated by this conjecture.