I searched for <<family of subsets closed under union “more than half”>> and the Wikipedia page about the conjecture was the first result :-).
It’s nothing wrong with the Googling method. Besides, one could search for <<pizzeria at the end of the world papa mamma>>. Should work now, too.
Maybe, next year’s solution to this problem will be “at least 13”.
I searched for <<family of subsets closed under union “more than half”>> and the Wikipedia page about the conjecture was the first result :-).
It’s nothing wrong with the Googling method. Besides, one could search for <<pizzeria at the end of the world papa mamma>>. Should work now, too.
Maybe, next year’s solution to this problem will be “at least 13”.