Evolution and gradualness.
Evolutionary systems are commonly considered to have fundamental properties: (1) elements (or organisms) in the system reproduce with mutation and (2) only the fit elements survive. I propose that evolutionary systems have a third property - the property of gradualness. A system has gradualness, if, and only if, small changes in an element usually lead to small changes in that element's fitness. I have formalized a framework from which attempts to design evolutionary systems might proceed. Of particular importance are the criteria, based on the notion of perpetuation, which a system's behavior must satisfy in order to be considered evolutionary. By my standards, no computer programs have been designed that manifest meaningful evolutionary behavior.
D005075:Biological Evolution; D008433:Mathematics; D008954:Models, Biological; D009154:Mutation