This paper describes the dynamics of adaptation in a two-country, overlapping generations economy with no restrictions on foreign currency holdings. Governments of both countries finance their deficits via seignorage. Agents in this economy are boundedly rational. They use the genetic algorithm...

We study the simple evolutionary process in which we repeatedly find the least fit agent in a population of agents and give it a new fitness which is chosen independently at random from a specified distribution. We show that many of the average properties of this process can be calculated...

During an immune response the affinity of antibodies that react with the antigen that triggered the response increases with time, a phenomenon known as affinity maturation. The molecular basis of affinity maturation has been partially elucidated. It involves the somatic mutation of immunoglobin...

To distinguish continuous from discontinuous evolutionary change, a relation of nearness between phenotypes is needed. Such a relation is based on the probability of one phenotype being accessible from another through changes in the genotype. This is exemplified by calculating the shape...