An elementary model of animal aggregation is presented. The gorup size distributions resulting from this model are truncated power laws. The predictions of the model are found to be consistent with data that describe the group size distributions of tuna fish, sardinellas, and African buffalos.<p> <p>...</p></p>

Computational mechanics, an approach to structural complexity, defines a process's causal states and gives a procedure for finding them. We show that the causal-state representation--an e-machine--is the minimal one consistent with accurate prediction. We establish several results on e-machine...

The fossil record of life has been shown to provide evidence for scaling laws in both time series and in some statistical features. This evidence was suggested to be linked with a self-organized critical phenomenon by several authors. In this paper we review some of these models and their...

A dynamical-systems-based model of computation is studied. We demonstrate the computational ability of nonlinear mappings. There exists a switching map system with two types of baker's map to emulate any Turing machine. Taking non-hyperbolic mappings with second-order nonlinearity (e.g., the...

This paper introduces a new analysis tool called {\it reverse hillclimbing}, and demonstrates how it can be used to evaluate the performance of a genetic algorithm. Using reverse hillclimbing, one can calculate the exact probability that hillclimbing will attain some point in a landscape. From...

The choice of how to represent the search space for a genetic algorithm (GA) is critical to the GA's performance. Representations are usually engineered by hand and fixed for the duration of the GA run. Here a new method is described in which the degrees of freedom of the representation---i.e....

We explore a simplified class of models we call swarms, which are inspired by the collective behavior of social insects. We perform a mean-field stability analysis and numerical simulations of the model. Several interesting types of behavior emerge in the vicinity of a second-order phase...

We introduce the concept of Adaptively Rational Equilibrium (A.R.E.) where agents base decisions upon predictions of future values of endogenous variables whose actual values are determined by equilibration. Predictors are chosen from a finite set. Each predictor is a function of past...

RNA secondary structure folding algoithms predict the existence of connected networks of RNA sequences with identical secondary structures. Fitness landscapes that are basedon the mapping between RNA sequence and RNA secondary structure hence have many neutral paths. A neutral walk on these...