The genesis of mathematical structures, as exemplified in the work of Charles Ehresmann
The aim of this paper is to present the great kinds of definitions known in mathematical logic, their goals and their means, from their historical and philosophical background (notably thanks to the proof of two theorems), and in order to situate, within this field, the others contributions which make up this number.
Analysis of some answers to the following questions : is there a generic notion of definition ? What is the difference between “analytic definition” and “synthetic definition” ? What is a good definition ?
L'article part d'une analogie entre trames et partitions, définitions conceptuelles et optiques. On montre que les divisions d'un espace de concepts ressemblent souvent à celles de l'espace réel. On étudie alors quelques exemples de pavage d'un espace conceptuel (Aristote) et on compare les processus dichotomiques platoniciens (générateurs de définitions) aux filtres d'une algèbre booléenne. Par la suite, on généralise ces modèles, considérant des structures floues et des «ensembles approximatifs»...