I discuss the relations among four worlds: Reality, mathematical models, computer simulation, and models of computation. Pros and cons of two models of computation, the Turing machine and the real number model, are presented. The the intrinsic difficulty of solving a mathematical model, as...

This paper provides a unified framework for studying the effects of economic (and other) institutions on the evolution of preferences, taking account of conformist cultural transmission, social segregation, and the simultaneous operation of selection processes at the individual and group level....

We use game theory and the Santa Fe Artificial Stock Market, an agent-based model of an evolving stock market, to study the properties of strategic Nash equilibria in financial markets. We discover two things: there is a unique strategic equilibrium in the market, and this equilibrium in...

Genetic relatedness is a central concept in the study of social evolution. Though originally defined in terms of genealogy, the modern version of relatedness accommodates genetic similarity of any origin. This paper examines relatedness in group structured models, in which a trait affects the...

Suppose a two-dimensional dynamical system has a stable attractor that is surrounded by an unstable limit cycle. If the system is additively perturbed by white noise, the rate of escape through the limit cycle will fall off exponentially as the noise strength. The presence of this slowly...

Can we build computers that are intelligent and alive? This question has been on the minds of computer scientists since the dawn of the computer age and remains a most compelling line of inquiry. Some would argue that the question makes sense only if we put scare quotes around "intelligent" and...

The notion of ``evolvability''---the ability of a population to produce variants fitter than any yet existing---is developed as it applies to genetic algortithms. A theoretical analysis of the dynamics of genetic programming predicts the existence of a novel, emergent selection phenomenon: the...

I raise questions regarding the unknown and the unknowable in science. I also briefly address two topics which have been much in the news in 1996, and which might erroneously be confused with my topic. These are, first, the book by John Horgan, called The End of Science, and second, the great...

In this review article, we explore several recent advances in the quantitative modeling of financial markets. We begin with the Efficient Markets Hypothesis and describe how this controversial idea has stimulated a number of new directions of research, some focusing on more elaborate...

The spatiotemporal behavior of the spread of influenza in France has been studied, and algebraic spatial correlations (with exponent ) spanning the whole territory have been found to be present as soon as the number of reported cases first starts to increase, about 15 to 25 weeks before the peak...