magnificent rectangular board, with a symbol in each sqaure
Source: Portugal OPM 2023 p6
May 15, 2024
combinatoricscombinatorial geometry
Problem Statement
A rectangular board, where in each square there is a symbol, is said to be magnificent if, for each line and for each pair of columns and , there is on the board another line exactly equal to , except in columns and , where has symbols different from those of . What is the smallest possible number of rows on a magnificent board with columns?