A number of different problems of interest to the operational researcher and the mathematical economist - for example, certain problems of optimization on graphs and networks, of machine-scheduling, of convex analysis and of approx imation theory - can be formulated in a convenient way using the algebraic structure (R, $, @) where we may think of R as the (extended) real-number system with the binary combining operations x$y, x(r)y defined to be max(x, y), (x+y) respectively. The use of this algebraic structure gives these problems the character of problems of linear algebra, or linear...