Show existence of method to buy 9 tickets.
Source:
December 31, 2011
combinatorics unsolvedcombinatorics
Problem Statement
In a lottery, a person must select six distinct numbers from to put on a ticket. The lottery commitee will then draw six distinct numbers randomly from . Any ticket with numbers not containing any of these numbers is a winning ticket. Show that there is a scheme of buying tickets guaranteeing at least one winning ticket, but tickets are not enough to guarantee a winning ticket in general.