Publication at Faculty of Mathematics and Physics |
2007
Abstract
We consider the number of nonnegative integer matrices with prescribed row-sums x_1,...,x_r and column sums y_1,...,y_c, with the additional property that no 3x3 submatrix has only positive entries on the main diagonal. We show that the number of such matrices only depends on the multiset {x_1,...,x_r,y_1,...,y_c}.