My lesson for today: "Sometimes, the reason that a conjecture is very hard to prove is simply that it is false." Worth to see: https://gilkalai.wordpress.com

My lesson for today: "Sometimes, the reason that a conjecture is very hard to prove is simply that it is false." Worth to see: https://gilkalai.wordpress.com/2019/05/10/sansation-in-the-morning-news-yaroslav-shitov-counterexamples-to-hedetniemis-conjecture/ https://gilkalai.wordpress.com/2019/05/10/sansation-in-the-m... Congratulations to Yaroslav Shitov!