Aggregating assignment constraints

This article shows how simple systems of linear equations with {0,1} variables can be aggregated into a single linear equation whose {0,1} solutions are identical to the solutions of the original system. Structures of the original systems are exploited to keep the aggregator's integer coefficients from becoming unnecessarily large. The results have potential application in integer programming and information theory, especially for problems that contain assignment-type constraints along with other constraints. Several unresolved questions of a number-theoretic nature are mentioned at the conclusion of the article.     

Time-minimizing transportation problems

A method is given for finding those solutions of a transportation problem which minimize the total time necessary for transporting goods from the suppliers to the consumers. Several extensions of the model are presented.     

Book Reviews

Men, Ideas and Tanks: British Military Thought and Armoured Forces, 1903–1939. By J. P. Harris, Manchester University Press, (1995) ISBN 0 7190 3762 (hardback) £40.00 or ISBN 0 7190 4814 (paperback) £14.99

Fighting for Ireland. By M. L. R. Smith. London and New York: Routledge, (1995) ISBN 0–415–09161–6.

The Fundamentals of British Maritime Doctrine (BR1806) HMSO London (1995) ISBN 0–11–772470‐X £9.50

Regional Conflicts: The Challenges to US‐Russian Co‐Operation Edited by James E. Goodby SIPRI: Oxford University Press 1995 ISBN 019‐S29–171X, £30.00

SIPRI Yearbook 1995 ‐ Armaments, Disarmament and International Security Oxford: Oxford University Press 1995. ISBN 019–829–1930, £60.00.

Drug Trafficking in the Americas Edited by Bruce M. Bagley & William O. Walker III Transaction Publishers, New Brunswick, (USA), 1994 ISBN 1–56000–752–4.

Raglan: From the Peninsula to the Crimea By John Sweetman, Arms & Armour 1993. ISBN 1–85409–059–3. £19.00.