Portuguese food - Portuguese MO, Problem 3, 2010
Source:
August 28, 2010
combinatorics proposedcombinatorics
Problem Statement
On each day, more than half of the inhabitants of Évora eats sericaia as dessert. Show that there is a group of 10 inhabitants of Évora such that, on each of the last 2010 days, at least one of the inhabitants ate sericaia as dessert.