Before starting, I would like to beg the reader's indulgence. This paper is not a survey, or even a balanced account mentioning related work. It is simply an exposition of one approach to the problem. As such it contains only three references — all to my own work! Mea culpa.

In each of the sciences there are pivotal problems which can be formalized as searches for the global optimum of a function f: A→R, where A is an appropriately chosen domain of elements and R is the set of positive real numbers. In genetics, for example, A becomes the genotypes (combinations of genes) of interest and f assigns to each genotype its fitness; in economics (von Neumann's model), A becomes mixes of economic activities and f assigns to each mix its utility; in game playing, A becomes the possible strategies and f assigns to each strategy its minimax value; and so on.