Hommage à Gérard Joncoux

Hommage to reactive psychosis.

When looking back in the history of psychiatry, the concept of reactivity had very variable impact on ethiological considerations. If classification of mental disorders is taken as a proxy, it seems that this impact is presently at the lowest that it has been in the last hundred years. The author gives a short historical overview of concept of reactive psychosis, followed by a description of th...

Gérard Maze and Lorenz

Cryptography based on Semigroup Actions ∗ Gérard Maze

A generalization of the original Diffie-Hellman key exchange in (Z/pZ) found a new depth when Miller [27] and Koblitz [16] suggested that such a protocol could be used with the group over an elliptic curve. In this paper, we propose a further vast generalization where abelian semigroups act on finite sets. We define a Diffie-Hellman key exchange in this setting and we illustrate how to build in...

6 Dynamics of trap models Gérard

3 The one-dimensional trap model 9 3.1 The Fontes-Isopi-Newman singular diffusion . . . . . . . . . . . . . . . . 10 3.2 The scaling limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.3 Aging results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.4 Subaging results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.5 Behaviour of t...

Identities , forgeries and disguises Gérard Chollet and

The preservation of your identity could become a major concern. In many situations, you need to claim an identity and this claim needs to be verified somehow. The technology called biometrics may help. But, what if a deliberate impostor claims your identity? Will this forgery be always detected? Biometric identity verification is imperfect. This paper reviews some of the techniques that a delib...