Question de Whitehead et modules précroisés
نویسندگان
چکیده
منابع مشابه
Whitehead Test Modules
A (right R-) module N is said to be a Whitehead test module for projectivity (shortly: a p-test module) provided for each module M , ExtR(M,N) = 0 implies M is projective. Dually, i-test modules are defined. For example, Z is a p-test abelian group iff each Whitehead group is free. Our first main result says that if R is a right hereditary non-right perfect ring, then the existence of p-test mo...
متن کاملAlgèbres de distributions et D-modules arithmétiques
Let p be a prime number, V a complete discrete valuation ring of unequal caracteristics (0, p), G a smooth affine algebraic group over Spec V . Using partial divided powers techniques of Berthelot, we construct arithmetic distribution algebras, with level m, generalizing the classical construction of the distribution algebra. We also construct the weak completion of the classical distribution a...
متن کاملWhitehead Modules over Large Principal Ideal Domains
We consider the Whitehead problem for principal ideal domains of large size. It is proved, in ZFC, that some p.i.d.’s of size ≥ א2 have nonfree Whitehead modules even though they are not complete discrete valuation rings. A module M is a Whitehead module if ExtR(M,R) = 0. The second author proved that the problem of whether every Whitehead Z-module is free is independent of ZFC + GCH (cf. [5], ...
متن کاملEvaluation de la réponse d'un système de question-réponse et de sa justification
RÉSUMÉ. Les systèmes de question-réponse fournissent une réponse à une question en l’extrayant d’un ensemble de documents. Avec celle-ci ils fournissent également un passage de texte permettant de la justifier. On peut alors chercher à évaluer si la réponse proposée par un système est correcte et justifiée par le passage. Pour cela, nous nous sommes fondés sur la vérification de différents crit...
متن کاملSéparation et propriété de Deligne-Mumford des champs de modules d'intersections complètes lisses
We show that the moduli stacks of smooth complete intersections in P polarized by O(1) are separated (except for quadrics) and Deligne–Mumford (apart from a few exceptions).
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Bulletin de la Société mathématique de France
سال: 1996
ISSN: 0037-9484,2102-622X
DOI: 10.24033/bsmf.2286