huinventors1-6, Exercise 3: A contribution that is not a device

Model answer (game theory):

Von Neumann proved in 1928 that in a certain kind of two-player contest there is a best strategy (the minimax theorem), and developed the theory in a book with Oskar Morgenstern in 1944. It is an idea and not a device, yet it is the basis of much of modern economics and decision-making. It counts as a contribution because it changed how problems were analysed and gave later workers tools to use, as Chapter 1 noted for a theory or design. Alternatives: Monte Carlo methods or self-reproducing machines. Details should be checked.