It is easy to verify that the sum of two Franklin squares is a Franklin square and that nonnegative integer multiples of Franklin squares are Franklin squares. Therefore,
the set of Franklin squares is the set of all integral points inside a pointed polyhedral
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cone C = {y ; Ay = 0, y > 0} in R" where A is the coefficient matrix of the defin¬ing linear system of equations. In the example of 8 x 8 Franklin squares, there are seven linear relations equating the first row sum to all other row sums and eight more equating the first row sum to column sums. Similarly, equating the eight half-row sums and the eight half-column sums to the first row sum generates sixteen linear equations. Equating the four sets of parallel bent diagonal sums to the first row sum produces another thirty-two equations. We obtain a further sixty-four equations by setting all the 2x2 subsquare sums equal to the first row sum. Thus, there are a total of 127 linear equations that define the cone of 8 x 8 Franklin squares. The coefficient matrix A has rank 54 and therefore the cone C of 8 x 8 Franklin squares has dimension 10 (see [14]).