Meurtriers, jumeaux et devins : Trois variations sur le thème du double (Bassar, Togo)1

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...

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 le théorème de Cassels, Ellison et Pfister

Artin [Ar] (1927) : Une fraction rationnelle f ∈ R(X1, . . . , Xn) positive sur R est une somme de carrés. Pfister [Pf] (1967) : c’est une somme de 2 carrés. En particulier pour n = 2, f ∈ 4 R(X,Y ). Cassels, Ellison, Pfister [CEP] (1971) : 4 carrés sont vraiment nécéssaires (i.e. le nombre de Pythagore de R(X, Y ) est 4, car le polynôme de Motzkin 1 + XY 4 + XY 2 − 3XY , positif ou nul, ne s’é...

Suite Du Mémoire Sur Le Calcul Des

I have observed at the same time that it was not necessary in this case to understand, by the proper probability of a fact, the ratio of the number of combinations where it takes place, with the total number of combinations. For example, if in a deck of ten cards one has drawn one of them, & if a witness says to me that this is such a card in particular, the proper probability of this fact, whi...

Recherches biochimiques et immunologiques sur le venin des serpents