We seek methods which produce all the solutions of a transportation problem
and which are applicable to more complex transportation problems. It is argued
that direct methods should be considered. While the purest direct method is not
practical, a modification substitutes some simple techniques for the minimization
condition. With the methods of reduced matrices, we make subtractions from the
rows and columns of the transportation matrix to produce a transformed matrix
with all elements non-negative such that the non-negative integral Xij can be
assigned to X the zero terms so as to satisfy the specifications for origins, i, and
destinations, j.
This work is a revised and extended version of an unpublished paper of 1955
[61. It is related to published work on (and machines programs for) more general
problems published in 1956 [7] and 1957 [9] and [171.