ELA, Volume 4, pp. 48-73, November 1998, abstract.
D-optimal weighing designs for four and five objects
Michael G. Neubauer, William Watkins, and Joel Zeitlin
For j=4 and j=5 and all d greater than or equal to j, the maximum
value of det XX^T, where X runs through all j times d (0,1)-matrices,
is determined along with a matrix X_0 for which the maximum determinant
is attained. In the theory of statistical designs, X_0 is called a
D-optimal design matrix. Design matrices that were previously thought
to be D-optimal, are shown here to be D-optimal.