eng] The role of social networks in innovation diffusion remains a strategic question. In former works, we have introduced a relational learning, based on hebbian rule, that leads to a critical state, in which few agents reach structural positions of opinion leaders. In this paper, we show that the self-organization of an influence network, through social learning, is not a monotonie process, from the point of view of structural characteristics as well as of its diffusion performances. The notion of intermediarity, which derives directly from the concept of network, appears necessary to decrypt this evolution. By introducing the role of "weak ties" in the diverse diffusion regimes it is then possible to bring a new understan-ding of the phenomenon.
[fre] Le rôle des réseaux sociaux dans la diffusion de l'innovation demeure une question stratégique. Dans des travaux antérieurs, nous avons introduit un apprentissage relationnel, de type hebbien, qui conduit à un état critique, dans lequel certains agents acquièrent des positions, purement structurelles, de leaders d'opinion. Dans cet article, nous montrons que l'auto-organisation d'un réseau d'influence, par l'effet d'un apprentissage social, ne constitue pas un phénomène monotone, aussi bien du point de vue des caractéristiques structurelles du réseau que de celui de ses performances en diffusion. Ceci nécessite, pour être analysé, de recourir à la notion d'intermédiarité qui est inhérente au concept de réseau. Une analyse relative au rôle des "liens faibles" dans les différents régimes de diffusion devrait alors permettre d'offrir un éclairage nouveau sur cette dynamique d'évolution.

[eng] Though software intellectual property could not satisfactorily fall into any existing legal framework, all countries have taken the decision to range it under the category of copyright. Then the double objective of intellectual property protection is not satisfied, which consists, on the one hand, to grant to the inventor a provisional monopoly for exploiting his invention and, on the other hand, to oblige him to disclose the principles of his invention. To resort to the patents system as it became more and more usual in the US and which is in debate in Europe, raise other kind of problems. Now the alternative model of Open Source Software, based on a very peculiar juridical tool called GPL « General Public Licence », tends to take a growing importance. Its main principle is to impose to its adopters to disclose the source-code of the concerned programs and of any further improvement, as well as the free circulation of the code under the sole condition to maintain its « open » character. A growing number of enterprises began to « free » part of their software products, by joining the GPL status or introducing their own « hybrid » licences, in order to control the extent of their openness. By doing that they introduce a totally different approach of intellectual property within their industrial strategies. [fre] Bien que, tant sur le plan juridique que sur le plan économique, la propriété intellectuelle du logiciel ne trouve une solution satisfaisante dans aucun des cadres existants disponibles, la totalité des législations a pris le parti de la classer dans la catégorie du droit d'auteur. Aussi, le double objectif de la protection de la propriété intellectuelle qui consiste, d'un côté, à accorder à l'inventeur un monopole temporaire pour l'exploitation de son invention et, de l'autre, à exiger de sa part qu'il dévoile les principes de son invention, n'est pas satisfait. Le recours aux brevets, qui est devenu de plus en plus courant aux É

After a long period of building, the microelectronics cluster in the Marseilles Metropolitan Area appears to have reached a critical size and investment dynamics capable to ensure its durability. In this paper we aim to enlighten such an assumption by analysing the nature of the process that led to the present situation. We shall study the modalities of actors local co-ordination, while they are dependent of industry and markets global constraints. This will enable us to understand how such local co-ordinations can provide or not the ground of a territorial anchorage. Classification JEL : L23, L63, O18, R3, R58.

We introduce negative relationships in a network of social influence whose agents cope with a binary opinion concerning two competing standards, and we explore the possible collective dynamics. A weak proportion of anticonformism leads to well known phenomenon of lock-in (collective agreement uppon one given opinion). Too much anticonformism generates persistent instability in individual opinions about technological standards. Now, we point out that an optimal dose of anticonformism can originate lock-outs: a minimal amount is necessary to depart from homogenous behaviors, but too much would prevent the rest of the society from reaching the opinions of anticonformists, and achieve the lock-out. Hence, our interaction-ist analysis points out specific conditions of demand as a possible reason for changing consumer behaviors in a context of standardization.