Spread of decisions in the corporate board network

Boards of large corporations sharing some of their directors are connected in complex networks. Boards are responsible for corporations' long-term strategy and are often involved in decisions about a common topic related to the belief in economical growth or recession. We are interested in understanding under which conditions a large majority of boards making a same decision can emerge in the network. We present a model where board directors are engaged in a decision making dynamics based on "herd behavior". Boards influence each other through shared directors. We find that imitation of colleagues and opinion bias due to the interlock do not trigger an avalanche of identical decisions over the board network, whereas the information about interlocked boards' decisions does. There is no need to invoke global public information, nor external driving forces. This model provides a simple endogenous mechanism to explain the fact that boards of the largest corporations of a country can, in the span of a few months, take the same decisions about general topics.Comment: to appear in Advances in Complex Systems, accepted on 27 Nov 200

Pattern formation and optimization in army ant raids

Army ant colonies display complex foraging raid patterns involving thousands of individuals communicating through chemical trails. In this paper we explore, by means of a simple search algorithm, the properties of these trails in order to test the hypothesis that their structure reflects an optimized mechanism for exploring and exploiting food resources. The raid patterns of three army ant species, {em Eciton hamatum}, {em Eciton burchelli} and {em Eciton rapax}, are analysed. The respective diets of these species involve large but rare, small but common, and a combination of large but rare and small but common, food sources. Using a model proposed by Deneubourg and collaborators, we simulate the formation of raid patterns in response to different food distributions. Our results indicate that the empirically observed raid patterns maximise return on investment, that is, the amount of food brought back to the nest per unit of energy expended, for each of the diets. Moreover, the values of the parameters that characterise the three optimal pattern-generating mechanisms are strikingly similar. Therefore the same behavioural rules at the individual level can produce optimal colony-level patterns. The evolutionary implications of these findings are discussed.Postprint (published version

Decision making dynamics in corporate boards

Members of boards of directors of large corporations who also serve together on an outside board, form the so called interlock graph of the board and are assumed to have a strong influence on each others' opinion. We here study how the size and the topology of the interlock graph affect the probability that the board approves a strategy proposed by the Chief Executive Officer. We propose a measure of the impact of the interlock on the decision making, which is found to be a good predictor of the decision dynamics outcome. We present two models of decision making dynamics, and we apply them to the data of the boards of the largest US corporations in 1999.Comment: 20 pages, 10 figures, submitte

Computing with bacterial constituents, cells and populations: from bioputing to bactoputing

The relevance of biological materials and processes to computing—aliasbioputing—has been explored for decades. These materials include DNA, RNA and proteins, while the processes include transcription, translation, signal transduction and regulation. Recently, the use of bacteria themselves as living computers has been explored but this use generally falls within the classical paradigm of computing. Computer scientists, however, have a variety of problems to which they seek solutions, while microbiologists are having new insights into the problems bacteria are solving and how they are solving them. Here, we envisage that bacteria might be used for new sorts of computing. These could be based on the capacity of bacteria to grow, move and adapt to a myriad different fickle environments both as individuals and as populations of bacteria plus bacteriophage. New principles might be based on the way that bacteria explore phenotype space via hyperstructure dynamics and the fundamental nature of the cell cycle. This computing might even extend to developing a high level language appropriate to using populations of bacteria and bacteriophage. Here, we offer a speculative tour of what we term bactoputing, namely the use of the natural behaviour of bacteria for calculating

Expecting the Unexpected: The Need for a Networked Terrorism and Disaster Response Strategy

This article appeared in Homeland Security Affairs (February 2007) v.3 no.1Since Hurricane Katrina, attention has focused on improving management of response to natural disasters and terrorist attacks. However, what if the current management approach is so fundamentally mismatched to the challenge at hand that, even when improved, it is still unequal to the task? This essay argues that terrorist attacks or natural disasters are likely to be so unpredictable that they frequently require improvised responses (as conventional hierarchical structures are ill-suited to such situations) and outlines a flexible and highly adaptive networked structure. Networked personal communication devices and applications that the general public can and will use in a disaster offer the possibility of a new networked strategy that can foster the 'swarm intelligence' needed in a disaster, in which a community, even an ad hoc one, is capable of a higher level of collective behavior than could be predicted from the capabilities of individual members.Approved for public release; distribution is unlimited

Marginally Stable Swarms Are Flexible and Efficient

A simple model of cooperative food retrieval in ants is introduced to illustrate how a many-body biological system such as a swarm can exhibit an efficient and flexible behavior if it is close to an instability, but in a region where structured patterns of activity can grow and be maintained.Un modèle simplifié de fourragement coopératif chez les fourmis est introduit pour illustrer l'idée qu'un système biologique collectif tel qu'un essaim peut être à la fois flexible et efficace si les paramètres comportementaux qui le caractérisent se situent au voisinage d'une zone d'instabilité, mais dans une région où une activité structurée peut se développer et se maintenir