This paper describes a range of methods which have been proposed to study interactions in economic and social contexts. By interactionsk, we refer to interdependences between individual decisions which are not mediated by markets. These types of models have been employed to understand phenonmena...

Large variations in stock prices happen with sufficient frequency to raise doubts about existing models, which all fail to account for non-Gaussian statistics. We construct simple models of a stock market, and argue that the large variations may be due to a crowd effect, where agents imitate...

We present empirical evidence that long-term evolutionary dynamics fall into three distinct classes, depending on whether adaptive evolutionary activity is absent (class 1), bounded (class 2), or unbounded (class 3). These classes are defined using three statistics: diversity, new evolutionary...

A simple mechanism is presented, based on ant-like agents, for routing and load balancing in telecommunications networks, following the initial works of Appleby and Stewart (1994) and Schoonderwoerd et al. (1997). In the present work, agents are very similar to those proposed by Schoonderwoerd...

We introduce a class of embedded-particle models for describing the emergent computational strategies observed in cellular automata (CAs) that were evolved for performing certain computational tasks. The models are evaluated by comparing their estimated performances with the actual performances...

In this paper we study the small-world network model of Watts and Strogatz, which mimics some aspects of the structure of networks of social interactions. We argue that there is one non-trivial length-scale in the model, analogous to the correlation length in other systems, which is well-defined...

We consider a model of platform adaptation in spatial voting focussing on the effect of abstention on the stability of the mean voter equilibrium. Two distinct approaches for modeling abstention are explored: (1) voters abstain if party platforms are too similar to each other and (2) voters...

How do organisms communicate honestly despite conflicts of interest? Over the past quarter-century, the "costly signalling" hypothesis -- that signal honesty can be ensured by appropriate signal cost -- has emerged as the dominant explanation for this puzzle. First proposed by Zahavi [1, 2] and...

The following model of political process is intended to be a moderately realistic representation of Florentine republicanism, during the period of the Renaissance (ca. 1300-1500). The model is composed of two parts: (a) patronage - namely, the building up of partisan networks through the...