Schedule of a school
Source: Russian TST 2019, Day 5 P1
March 22, 2023
combinatoricsgraph theory
Problem Statement
A school organizes optional lectures for 200 students. At least 10 students have signed up for each proposed lecture, and for any two students there is at most one lecture that both of them have signed up for. Prove that it is possible to hold all these lectures over 211 days so that no one has to attend two lectures in one day.