Variations autour du thème - médecine et sciences

Spécialisation et sous-typage : thème et variations

Class specialization is the most original feature of object orientation, but identifying it to subtyping leads to the well known covariance-contravariance controversy. Type safety requires contravariance while specialization needs covariance. This paper aims to precisely analyse this problem, to show how irreductible it is and the need for type errors. We show that many alternatives as multiple...

Variations sur un THème de Aldama et Shelah

We study the definability of certain subgroups of a group G that does not have the independence property. If a (type) definable subset X of an elementary extension G of G has property P , we call its trace X∩G over G an externally (type) definable P set. We show the following. Centralisers of subsets of G are externally definable subgroups. Cores of externally definable subgroups and iterated c...

Combinatoire autour du groupe symétrique

La Médecine des lumières: tout autour de Tissot

any formal qualifications prior to the demonstration with ether is also confirmed. Interweaving the traditional story with his new information, Wolfe leads the reader through a very different tale of the introduction of ether by a man not conditioned by scientific training and lacking in moral principles. The notion is raised that it was Charles T Jackson who put the idea for the use of ether i...

Géométrie Projective : autour du programme de l’agrégation

Les sections du texte suivant détaillent les points du programme. Il y a aussi une section sur la liaison affine-projectif (qui est sous-jacente quand on parle d’éléments à l’infini) et une section sur la dualité projective, qui apporte un éclairage intéressant sur la dualité pour les espaces vectoriels. Par contre, on ne dit rien des quadriques projectives (on peut voir à ce sujet [Sam] chap. ...