Definitions of stigmergy

From a special Issue of Artificial Life on Stigmergy

Volume 5, Issue 2 / Spring 1999

Eric Bonabeau

In a call for paper for this special edition Eric Bonabeau, Santa Fe Institute described stigmergy:

The concept of stigmergy was introduced by Pierre-Paul Grasse in the 1950's to describe the indirect communication taking place among individuals in social insect societies. Stigmergy was originally defined by Grasse in his studies on the reconstruction of termite nests. Grasse showed that the regulation and coordination of the building activity do not depend on the workers themselves but is mainly achieved by the nest: a stimulating configuration triggers a response of a termite worker, transforming the configuration into another configuration that may trigger in turn another, possibly different, action performed by the same termite or any other worker in the colony. Although Grasse's concept of stigmergy was attractive and stimulating, it has been overlooked by students of social insects because it left open the important operational issue of how stimuli must be organized in time and space to allow perfect coordination. Despite the vagueness of Grasse's formulation, stigmergy is a profound concept, the consequences of which are yet to be explored. Not only is stigmergy of potential importance for our understanding of the evolution and maintenance of sociality in animals, from communally breeding species to highly eusocial insects, it may also turn out to be a crucial concept in other fields, such as artificial intelligence, robotics, or the social, political and economic sciences, to which its relevance is intuitively obvious. The aims of this special issue of Artificial Life on stigmergy are: - to provide readers from a variety of fields with an overview of what is known (and what is not) about stigmergy in such various contexts as ethology, distributed problem-solving and robotics, - to invite researchers in these fields to present their new work, - and to give the opportunity to researchers from other scientific communities to present their work in the light of stigmergy.

Guy Theraulaz and Eric Bonabeau

Guy Theraulaz and Eric Bonabeau described stigmergy:

Stigmergy is a class of mechanisms that mediate animal-animal interactions. Its introduction in 1959 by Pierre-Paul Grasse made it possible to explain what had been until then considered paradoxical observations. In an insect society individuals work as if they were alone while their collective activities appear to be coordinated. In this article we describe the history of stigmergy in the context of social insects and discuss the general properties of two distinct stigmergic mechanisms: quantitative stigmergy and qualitative stigmergy.

Istvan Karsai

Istvan Karsai described stigmergy:

Grasse coined the term stigmergy (previous work directs and triggers new building actions) to describe a mechanism of decentralized pathway of information flow in social insects. In general, all kinds of multi-agent groups require coordination for their effort and it seems that stigmergy is a very powerful means to coordinate activity over great spans of time and space in a wide variety of systems. In a situation in which many individuals contribute to a collective effort, such as building a nest, stimuli provided by the emerging structure itself can provide a rich source of information for the working insects. The current article provides a detailed review of this stigmergic paradigm in the building behavior of paper wasps to show how stigmergy influenced the understanding of mechanisms and evolution of a particular biological system. The most important feature to understand is how local stimuli are organized in space and time to ensure the emergence of a coherent adaptive structure and to explain how workers could act independently yet respond to stimuli provided through the common medium of the environment of the colony.