Conditional Matrices
Source: 2009 MMO Problem #3
September 12, 2011
linear algebramatrixcombinatorics unsolvedcombinatorics
Problem Statement
Decide whether the integers can be arranged in the cells of a matrix (where ), such that the following conditions are fullfiled:
i) In every row, the entries add up to the same sum .
ii) In every column, the entries also add up to this sum .
iii) For every the ten entries with add up to .
(Proposed by Gerhard Woeginger, Austria)